Dibenzorhodamine dyes

ABSTRACT

Dibenzorhodamine compounds having the structure ##STR1## are disclosed, including nitogen- and aryl-substituted forms thereof. In addition, intermediates useful for synthesizing such compounds are disclosed, such intermediates having the structure ##STR2## In Formula I, R 1  is H or ##STR3## wherein Y is H, lower alkyl, lower alkene, lower alkyne, aromatic, phenyl, polycyclic aromatic, heterocycle, water-solubilizing group, or linking group, including substituted forms thereof. When R 1  is H, the C-12-bonded nitrogen and the C-12 and C-13 carbons form a first ring structure having from 4 to 7 members, and/or the C-12-bonded nitrogen and the C-11 and C-12 carbons form a second ring structure having from 5 to 7 members. The compounds of Formula I further include aryl- and nitrogen-substituted forms thereof. The invention further includes energy transfer dyes comprising the dibenzorhodamine compounds, nucleosides labeled with the dibenzorhodamine compounds, and nucleic acid analysis methods employing the dibenzorhodamine compounds.

This is a continuation-in-part of application Ser. No. 08/978,775, filed Nov. 25, 1997, now U.S. Pat. No. 5,936,087.

FIELD OF THE INVENTION

This invention relates generally to fluorescent dye compounds. More specifically, this invention relates to modified rhodamine dyes useful as fluorescent labeling reagents.

BACKGROUND

The non-radioactive detection of biological analytes utilizing fluorescent labels is an important technology in modern molecular biology. By eliminating the need for radioactive labels, safety is enhanced and the environmental impact and costs associated with reagent disposal is greatly reduced. Examples of methods utilizing such non-radioactive fluorescent detection include 4-color automated DNA sequencing, oligonucleotide hybridization methods, detection of polymerase-chain-reaction products, immunoassays, and the like.

In many applications it is advantageous to employ multiple spectrally distinguishable fluorescent labels in order to achieve independent detection of a plurality of spatially overlapping analytes, e.g., single-tube multiplex DNA probe assays and 4-color automated DNA sequencing methods. In the case of multiplex DNA probe assays, by employing spectrally distinguishable fluorescent labels, the number of reaction tubes may be reduced thereby simplifying experimental protocols and facilitating the production of application-specific reagent kits. In the case of 4-color automated DNA sequencing, multicolor fluorescent labeling allows for the analysis of multiple bases in a single lane thereby increasing throughput over single-color methods and reducing uncertainties associated with inter-lane electrophoretic mobility variations.

Assembling a set of multiple spectrally distinguishable fluorescent labels is problematic. Multi-color fluorescent detection imposes at least six severe constraints on the selection of dye labels, particularly for applications requiring a single excitation light source, an electrophoretic separation, and/or treatment with enzymes, e.g., automated DNA sequencing. First, it is difficult to find a set of structurally similar dyes whose emission spectra are spectrally resolved, since the typical emission band half-width for organic fluorescent dyes is about 40-80 nanometers (nm). Second, even if dyes with non-overlapping emission spectra are identified, the set may still not be suitable if the respective fluorescent quantum efficiencies are too low. Third, when several fluorescent dyes are used concurrently, simultaneous excitation becomes difficult because the absorption bands of the dyes are usually widely separated. Fourth, the charge, molecular size, and conformation of the dyes must not adversely affect the electrophoretic mobilities of the analyte. Fifth, the fluorescent dyes must be compatible with the chemistry used to create or manipulate the analyte, e.g., DNA synthesis solvents and reagents, buffers, polymerase enzymes, ligase enzymes, and the like. Sixth, the dye must have sufficient photostability to withstand laser excitation.

Currently available multiplex dye sets suitable in 4-color automated DNA sequencing applications require blue or blue-green laser light to adequately excite fluorescence emissions from all of the dyes making up the set, e.g., argon-ion lasers. Use of Blue or blue-green lasers in commercial automated DNA sequencing systems is disadvantageous because of the high cost and limited lifetime of such lasers.

SUMMARY

The present invention is directed towards our discovery of a class of dibenzorhodamine dye compounds suitable for the creation of sets of spectrally-resolvable fluorescent labels useful for multi-color fluorescent detection. The subject dye compounds are particularly well suited for use in automated 4-color DNA sequencing systems using an excitation light source having a wavelength greater than about 630 nm, e.g., a helium-neon gas laser or a solid state diode laser.

In a first aspect, the invention comprises dibenzorhodamine dye compounds having the structure ##STR4## including nitrogen- and aryl-substituted forms thereof

In a second aspect, the invention comprises intermediates useful for the synthesis of dibenzorhodamine compounds having the structure ##STR5##

In Formula I, R₁ is H or ##STR6## wherein Y is H, lower alkyl, lower alkene, lower alkyne, aromatic, phenyl, polycyclic aromatic, heterocycle, water-solubilizing group, or linking group, including substituted forms thereof When R₁ is H, the C-12-bonded nitrogen and the C-12 and C-13 carbons form a first ring structure having from 4 to 7 members, and/or the C-12-bonded nitrogen and the C-11 and C-12 carbons form a second ring structure having from 5 to 7 members. The compounds of Formula I further include aryl- and nitrogen-substituted forms thereof

In a third aspect, the invention includes energy transfer dye compounds comprising a donor dye, an acceptor dye, and a linker linking the donor and acceptor dyes. The donor dye is capable of absorbing light at a first wavelength and emitting excitation energy in response, and the acceptor dye is capable of absorbing the excitation energy emitted by the donor dye and fluorescing at a second wavelength in response. The linker serves to facilitate the efficient transfer of energy between the donor dye and the acceptor dye. According to the present invention, at least one of the donor and acceptor dyes is a dibenzorhodamine dye having the structure set forth above.

In a fourth aspect, the present invention includes labeled nucleoside/tides having the structure

    NUC--D

wherein NUC is a nucleoside/tide or nucleoside/tide analog and D is a dibenzorhodamine dye compound having the structure set forth above. According to the invention, NUC and D are connected by a linkage wherein the linkage is attached to D at one of the substituent positions. Furthermore, if NUC comprises a purine base, the linkage is attached to the 8-position of the purine, if NUC comprises a 7-deazapurine base, the linkage is attached to the 7-position of the 7-deazapurine, and if NUC comprises a pyrimidine base, the linkage is attached to the 5-position of the pyrimidine.

In a fifth aspect, the invention includes polynucleotide analysis methods comprising the steps of forming a set of labeled polynucleotide fragments labeled with a dibenzorhodamine dye having the structure set forth above, subjecting the labeled polynucleotide fragments to a size-dependent separation process, e.g., electrophoresis, and detecting the labeled polynucleotide fragments subsequent to the separation process.

Various aspects of the above-described invention achieve one or more of the following important advantages over known fluorescent dye compounds useful for multiplex fluorescent detection: (1) the subject dye compounds may be efficiently excited by a low-cost red laser using wavelengths at or above 630 nm; (2) the emission spectra of the subject dye compounds can be modulated by minor variations in the type and location of nitrogen and/or aryl-substituents, allowing for the creation of dye sets having similar absorption characteristics yet spectrally resolvable fluorescence emission spectra; (3) the subject dye compounds may be easily attached to nucleosides/tides or polynucleotides without compromising their favorable fluorescence properties; (4) the subject dye compounds have narrow emission bandwidths, i.e., the emission bandwidth has a full-width at half the maximum emission intensity of below about 70 nm; (5) the subject dye compounds are highly soluble in buffered aqueous solution while retaining a high quantum yield; (6) the subject dye compounds are relatively photostable; and (7) the subject dye compounds have relatively large extinction coefficients, i.e., greater than about 50,000.

These and other features and advantages of the present invention will become better understood with reference to the following description, figures, and appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1-3 show exemplary synthetic pathways for the synthesis of the 1-amino-3-hydroxynapthalene intermediates of the invention.

FIG. 4 shows a generalized synthetic pathway for the synthesis of the dibenzorhodamine dye compounds of the invention.

FIGS. 5 and 6 show exemplary synthetic pathways for the synthesis of the dibenzorhodamine dye compounds of the invention.

FIG. 7 shows the structures of several exemplary dibenzorhodamine dye compounds of the invention.

FIG. 8 shows a synthesis of compound 18.

FIG. 9 shows a synthesis of compounds 57-61.

FIG. 10 shows a synthesis of compound 67.

FIG. 11 shows a synthesis of compound 72.

FIG. 12 shows a synthesis of compound 76.

FIG. 13 shows a synthesis of compound 81.

FIG. 14 shows a synthesis of compounds 82-84.

FIG. 15 shows a synthesis of compound 85.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents, which may be included within the invention as defined by the appended claims.

Generally, the present invention comprises a novel class of dibenzorhodamine dye compounds useful as fluorescent labels, methods and intermediates for synthesis of such dyes, reagents employing such dyes, and methods utilizing such dyes and reagents in the area of analytical biotechnology. The compounds of the present invention find particular application in the area of fluorescent nucleic acid analysis, e.g., automated DNA sequencing and fragment analysis, detection of probe hybridization in hybridization arrays, detection of nucleic acid amplification products, and the like.

I. Definitions

Unless stated otherwise, the following terms and phrases as used herein are intended to have the following meanings:

"Spectral resolution" in reference to a set of dyes means that the fluorescent emission bands of the dyes are sufficiently distinct, i.e., sufficiently non-overlapping, that reagents to which the respective dyes are attached, e.g. polynucleotides, can be distinguished on the basis of a fluorescent signal generated by the respective dyes using standard photodetection systems, e.g. employing a system of band pass filters and photomultiplier tubes, charged-coupled devices and spectrographs, or the like, as exemplified by the systems described in U.S. Pat. Nos. 4,230,558, 4,811,218, or in Wheeless et al, pgs. 21-76, in Flow Cytometry: Instrumentation and Data Analysis (Academic Press, New York, 1985).

"Heterocycle" means cyclic compounds in which one or more ring atoms are not carbon, i.e., are hetero atoms. Exemplary heterocycles include but are not limited to pyrrole, indole, furan, benzofuran, thiophene, benzothiophene and other like structures.

"Linking group" means a moiety capable of reacting with a "complementary functionality" attached to a reagent or member of an energy transfer dye pair, such reaction forming a "linkage" connecting the dye to the reagent or member of the energy transfer dye pair. Preferred linking groups include isothiocyanate, sulfonyl chloride, 4,6-dichlorotriazinyl, succinimidyl ester, or other activated carboxylates whenever the complementary functionality is amine. Preferably the linking group is maleimide, halo acetyl, or iodoacetamide whenever the complementary functionality is sulfhydryl. See R. Haugland, Molecular Probes Handbook of Fluorescent Probes and Research Chemicals, Molecular probes, Inc. (1992). In a particularly preferred embodiment, the ling group is a N-hydroxysuccinimidyl (NHS) ester and the complementary functionality is an amine, where to form the NHS ester, a dye of the invention including a carboxylate group is reacted with dicyclohexylcarbodiimide and N-hydroxysuccinimide.

"Substituted" as used herein refers to a molecule wherein one or more hydrogen atoms are replaced with one or more non-hydrogen atoms, functional groups or moieties. For example, an unsubstituted nitrogen is --NH₂, while a substituted nitrogen is --NHCH₃. Exemplary substituents include but are not limited to halo, e.g., fluorine and chlorine, lower alkyl, lower alkene, lower alkyne, sulfate, sulfonate, sulfone, amino, ammonium, amido, nitrile, lower alkoxy, phenoxy, aromatic, phenyl, polycyclic aromatic, heterocycle, water-solubilizing group, and lining group.

"Polycyclic aromatic" means aromatic hydrocarbons having multiple ring structures including biaryls and condensed benzenoid hydrocarbons. The biaryls are benzenoid compounds where two or more rings are linked together by a single bond. The parent system of this class is biphenyl. The condensed benzenoid compounds are characterized by two or more benzene rings fused together at ortho positions in such a way that each pair of rings shares two carbons. The simplest members of this group are napthalene, with two rings, and anthracene and phenanthrene, each with three rings.

"Lower alkyl" denotes straight-chain and branched hydrocarbon moieties containing from 1 to 8 carbon atoms, e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, sec-butyl, neopentyl, tert-pentyl, and the like.

"Lower alkene" denotes a hydrocarbon containing from 1 to 8 carbon atoms wherein one or more of the carbon-carbon bonds are double bonds.

"Lower alkyne" denotes a hydrocarbon containing from 1 to 8 carbon atoms wherein one or more of the carbons are bonded with a triple bond.

"Nucleoside" refers to a compound consisting of a purine, deazapurine, or pyrimidine nucleoside base, e.g., adenine, guanine, cytosine, uracil, thymine, deazaadenine, deazaguanosine, and the like, linked to a pentose at the 1' position. When the nucleoside base is purine or 7-deazapurine, the sugar moiety is attached at the 9-position of the purine or deazapurine, and when the nucleoside base is pyrimidine, the sugar moiety is attached at the 1-position of the pyrimidine, e.g., Kornberg and Baker, DNA Replication, 2nd Ed. (Freeman, San Francisco, 1992). The term "nucleotide" as used herein refers to a phosphate ester of a nucleoside, e.g., triphosphate esters, wherein the most common site of esterification is the hydroxyl group attached to the C-5 position of the pentose. The term "nucleoside/tide" as used herein refers to a set of compounds including both nucleosides and nucleotides. "Analogs" in reference to nucleosides/tides include synthetic analogs having modified base moieties, modified sugar moieties and/or modified phosphate moieties, e.g. described generally by Scheit, Nucleotide Analogs (John Wiley, New York, 1980). Phosphate analogs comprise analogs of phosphate wherein the phosphorous atom is in the +5 oxidation state and one or more of the oxygen atoms is replaced with a non-oxygen moiety. Exemplary analogs include but are not limited to phosphorothioate, phosphorodithioate, phosphoroselenoate, phosphorodiselenoate, phosphoroanilothioate, phosphoranilidate, phosphoramidate, boronophosphates, including associated counterions, e.g., H⁺, NH₄ ⁺, Na⁺, if such counterions are present. Exemplary base analogs include but are not limited to 2,6-diaminopurine, hypoxanthine, pseudouridine, C-5-propyne, isocytosine, isoguanine, 2-thiopyrimidine, and other like analogs. Exemplary sugar analogs include but are not limited to 2'- or 3'-modifications where the 2'- or 3'-position is hydrogen, hydroxy, alkoxy, e.g., methoxy, ethoxy, allyloxy, isopropoxy, butoxy, isobutoxy and phenoxy, amino or alkylamino, fluoro, chloro and bromo. The term "labeled nucleoside/tide" refers to nucleosides/tides which are covalently attached to the dye compounds of Formula I through a linkage.

"Water solubilizing group" means a substituent which increases the solubility of the compounds of the invention in aqueous solution. Exemplary water-solubilizing groups include but are not limited to quaternary amine, sulfate, sulfonate, carboxylate, phosphate, polyether, polyhydroxyl, and boronate.

"Polynucleotide" or "oligonucleotide" means polymers of natural nucleotide monomers or analogs thereof, including double and single stranded deoxyribonucleotides, ribonucleotides, α-anomeric forms thereof, and the like. Usually the nucleoside monomers are linked by phosphodiester linkages, where as used herein, the term "phosphodiester linkage" refers to phosphodiester bonds or bonds including phosphate analogs thereof including associated counterions, e.g., H⁺, NH⁺, Na⁺, if such counterions are present. Polynucleotides typically range in size from a few monomeric units, e.g. 5-40, to several thousands of monomeric units. Whenever a polynucleotide is represented by a sequence of letters, such as "ATGCCTG," it will be understood that the nucleotides are in 5'→3' order from left to right and that "A" denotes deoxyadenosine, "C" denotes deoxycytidine, "G" denotes deoxyguanosine, and "T" denotes deoxythymidine, unless otherwise noted.

"Rhodamine dye" refers to dyes including the general polycyclic structure ##STR7## including any and all substituted versions thereof II. 1-Amino-3-Hydroxynapthalene Intermediates

A. Structure

In a first aspect, the present invention comprises a novel class of 1-amino-3-hydroxynapthalene compounds useful as intermediates in the synthesis of dibenzorhodamine dyes. These compounds have the general structure shown in Formula I immediately below, including substituted forms thereof In Formula I, R₁ is H or ##STR8## wherein Y is H, lower alkyl, lower alkene, lower alkyne, aromatic, phenyl, polycyclic aromatic, heterocycle, water-solubilizing group, or linking group, including substituted forms thereof When R₁ is X the C-12-bonded nitrogen and the C-12 and C-13 carbons form a first ring structure having from 4 to 7 members, and/or the C-12-bonded nitrogen and the C-11 and C-12 carbons form a second ring structure having from 5 to 7 members. The compounds of Formula I further include aryl- and nitrogen-substituted forms thereof (Note that all molecular structures provided herein are intended to encompass not only the exact electronic structures presented, but also include all resonant structures, protonation states and associated counterions thereof.) ##STR9##

In one preferred embodiment of the compounds of Formula I, Y is phenyl or substituted phenyl, the phenyl having the structure ##STR10## Substituents at any one of positions C-14 to C-18 may be any suitable substituent. Preferably, the substituents are chlorine, fluorine, lower alkyl, carboxylic acid, sulfonic acid, --CH₂ OH, alkoxy, phenoxy, linking group, water solubilizing group, and substituted forms thereof. In a particularly preferred embodiment, a substituent at position C-18 is selected from the group consisting of carboxylic acid and sulfonate, most preferably carboxylic acid. In another particularly preferred embodiment, a substituent at positions C-14 and C-17 is chlorine. In another preferred embodiment, a substituent at positions C-14 to C-17 is chlorine or fluorine. In yet another particularly preferred embodiment, a substituent at one of positions C-15 and C-16 is linking group and the other is hydrogen, a substituent at positions C-14 and C-17 is chlorine, and a substituent at position C-18 is carboxy.

In another preferred embodiment of the compounds of Formula I, the C-12-bonded nitrogen and the C-12 and C-13 carbons form a first ring structure having from 4 to 7 members, and/or the C-12-bonded nitrogen and the C-11 and C-12 carbons form a second ring structure having from 5 to 7 members. More preferably, the first and/or second ring structure has five members, where preferably the five membered ring structure includes one gem disubstituted carbon. Preferably, the gem substituents are lower alkyl, e.g., methyl. In another preferred embodiment, the five membered ring is substituted with linking group. In this preferred embodiment wherein the C-12-bonded nitrogen and the C-12 and C-13 carbons form a first ring structure having from 4 to 7 members, and/or the C-12-bonded nitrogen and the C-11 and C-12 carbons form a second ring structure having from 5 to 7 members, R₁ may be H or ##STR11## wherein Y is H, lower alkyl lower alkene, lower alkyne, aromatic, phenyl, polycyclic aromatic, heterocycle, water-solubilizing group, or linking group, including substituted forms thereof.

In yet another preferred embodiment of the compounds of Formula I, the compounds include a substituted nitrogen. Preferred nitrogen substituents include lower alkyl lower alkene, lower alkyne, phenyl, aromatic, heterocycle, polycyclic aromatic, water-solubilizing group, lining group, and substituted forms thereof More preferably, the nitrogen substituents are lower alkyl, phenyl, or substituted forms thereof, wherein preferred substituents are linking group, sulfonate or water-solubilizing group. Exemplary water-solubilizing groups are carboxylate, sulfonate, phosphate, quaternary amine, sulfate, polyhydroxyl, and water-soluble polymer. In a particularly preferred embodiment, the nitrogen substituent is --L--R, wherein L may be any linker and R is linking group or water-solubilizing group. In a particularly preferred embodiment, L is, ##STR12## or --(CH₂)-- where n ranges from 1 to 8. In another particularly preferred embodiment, the water solubilizing group is carboxylate, sulfonate, phosphate, quaternary amine, sulfate, polyhydroxyl, and water-soluble polymer.

In yet another preferred embodiment, the compounds of Formula I include one or more substituents at one or more of positions C-8 to C-11, and C-13. Preferred substituents include fluorine, chlorine, lower alkyl lower alkene, lower alkyne, sulfate, sulfonate, sulfone, sulfonamide, sulfoxide, amino, ammonium, amido, nitrile, lower alkoxy, phenoxy, aromatic, phenyl, polycyclic aromatic, water-solubilizing group, heterocycle, and linking group, including substituted forms thereof In a particularly preferred embodiment, the compound includes a fused aromatic ring bonded across the C-9 and C-10 carbons, or across the C-10 and C-11 carbons, including substituted forms thereof, where a particularly preferred substituent is sulfonate.

Several representative 1-amino-3-hydroxynapthalene compounds of the invention are shown in FIGS. 1-3, i.e., compounds 4, 9, 15, 17, 22, 27 and 29, and FIGS. 10-13, i.e., compounds 62, 63, 68, 73 and 80.

B. Synthetic Methods

Several synthetic methods are available for the synthesis of the 1-amino-3-hydroxynapthalene compounds described above, different methods being preferred depending on the nature of the ring structure and the nitrogen substituents of the particular compound to be synthesized.

A first preferred synthesis method suitable for the synthesis of 1-substituted-amino-3-hydroxynapthalene compounds, e.g., 1-diethylamino-3-hydroxynapthalene 4, is shown in FIG. 1. In this first method, a 3-methoxy-1-hydroxy napthalene 1 is reacted with dry triethylamine and trifluoromethanesulfonic anhydride to form a crude 3-methoxynapthalene-1-triflate 2. The triflate 2 is then reacted with an amine, e.g., a secondary amine, e.g., diethylamine, using palladium catalyzed triflate/amine coupling to form the substituted amine compound 3. Compound 3 is then deprotected using a boron tribromide deprotection procedure to produce the 1-amino-3-hydroxynapthalene product, e.g., 1-diethylamino-3-hydroxynapthalene 4. An example of this synthesis is provided in Example 1 below.

A second preferred synthesis method suitable for the synthesis of benzoindoline compounds, e.g., N-phenyl-3,3-dimethyl-4-hydroxy-benzoindoline 9, is also shown in FIG. 1. In this method, the 3-methoxynapthalene-1-triflate 2 is derivatized with a primary amine, e.g., aniline, using a palladium catalyzed triflate coupling reaction to give a secondary amine, e.g., 1-anilino-3-methoxynapthalene 5. The secondary amine 5 is acetylated using an acid chloride, e.g., an haloacetylchloride, to give a disubstituted amide, e.g., 1-amido-3-methoxynapthalene 6. The tertiary amide 6 is cyclized using a Lewis-acid-catalyzed Friedel-Crafts cyclization procedure to give compound 7, e.g., using AlCl₃. Coumpound 7 is than reduced, e.g., using (lithium aluminum hydride) LAH, to give coumpound 8. Subsequent methoxy group deprotection by a boron tribromide deprotection procedure gives the benzoindoline, e.g., N-phenyl-3,3-dimethyl-4-hydroxy-benzoindoline 9. An example of this synthesis is provided in Example 2 below.

A third preferred synthesis method suitable for the synthesis of N-substituted-5-hydroxy-(tetrahydro)benzoquinoline compounds, e.g., N-methyl-5-hydroxy-(tetrahydro)benzoquinoline 15, is shown in FIG. 2. In this method, compound 10 is synthesized from methoxy-napthaldehyde by condensation with malonic acid using a piperidine catalyst in pyridine. Compound 10 is then reduced with hydrogen, followed by LAH reduction, and reacted with trifluoromethanesulfonic anhydride to give the triflate 11. The triflate 11 is reacted with NaN₃ to give compound 12. Compound 12 is complexed with a Lewis acid, e.g., AlCl₃, and refluxed yielding the cyclized benzoquinoline derivative 13. Next, a nitrogen substituent is added, e.g., the nitrogen is alkylated using a conventional alkylation procedure, e.g., the benzoquinoline derivative 13 is reacted with with n-butyl lithium and an alkylating agent, e.g., MeI to give compound 14 or propane sultone to give compound 16. The methoxy group is then removed by a boron tribromide procedure giving a N-alkylbenzoquinoline derivative, e.g., compound 15 or 17. An example of this synthesis is provided in Example 3 below.

A fourth preferred synthesis method suitable for the synthesis of N-substituted-2,2,4-trimethyl-5-hydroxy-benzoquinoline compounds, e.g of N-methyl-2,2,4-trimethyl-5-hydroxy-(tetrahydro)benzoquinoline 22, is shown in FIG. 3. In this method, following the procedure of A. Rosowsky and E. J. Modest (J.O.C. 30 1832 1965, and references therein), 1-amino-3-methoxynapthalene 18 is reacted with acetone catalyzed by iodine and then quenched with saturated Na₂ S₂ O₃ to give the benzoquinoline compound 19. Compound 19 is then alkylated with an alkylating agent, e.g., MeI, according to a general alkylation procedure to give compound 20. The alkylated compound 20 is reduced with H₂ catalyzed by Pd/C to give a N-methyl-methoxyquinoline intermediate 21, and subsequent methoxy group deprotection by a general boron tribromide procedure yields the N-substituted-2,2,4-trimethyl-5-hydroxy-benzoquinoline compound, e.g., N-methyl-2,2,4-trimethyl-5-hydroxy-(tetrahydro)benzoquinoline 22. An example of this synthesis is provided in Example 4 below.

A fifth preferred general synthesis method suitable for the synthesis of N-substituted-3,3-dimethyl-4-hydroxy-benzoindoline compounds, e.g N-methyl-3,3-dimethyl-4-hydroxy-benzoindoline 27, is also shown in FIG. 3. In this method, a 1-amino-3-methoxynapthalene 18 is acetylated with an acid chloride, e.g., 2-bromo-2-methylpropionyl chloride, to give compound 23. Compound 23 is cyclized by reaction with AlCl₃ to give compound 24. Compound 24 is then reduced with LAH to give the 3,3-dimethyl-4-methoxybenzoindoline 25. Compound 25 is then alkylated with an alkylating agent, e.g., methyl iodide, to give a N-methyl-3,3-dimethyl-4-methoxybenzoindoline, e.g., compound 26. Subsequent methoxy group deprotection by with boron tribromide gives compound 27. An example of this synthesis is provided in Example 5 below.

III. Dibenzorhodamine Dye Compounds

A. Structure

In a second aspect, the present invention comprises a novel class of dibenzorhodamine dye compounds useful as molecular labels having the general structure shown in Formula II immediately below, including aryl- and nitrogen-substituted forms thereof. ##STR13##

In one preferred embodiment of the compound of Formula II, the compound includes a first bridging group which when taken together with the C-12-bonded nitrogen and the C-12 and C-13 carbons forms a first ring structure having from 4 to 7 members, and/or a second bridging group which when taken together with the C-2-bonded-nitrogen and the C-1 and C-2 carbons forms a second ring structure having from 4 to 7 members. More preferably, one or both of the first and second ring structures has five members. In yet a more preferred embodiment, the five membered ring structure includes one gem disubstituted carbon, wherein the gem substituents are lower alkyl, e.g., methyl. In an alternative preferred embodiment, the five membered ring is substituted with linking group. In another preferred embodiment, the five membered ring includes one or more nitrogen substituents, as described below.

In another preferred embodiment, the compound of Formula II includes a C-7 substituent selected from the group consisting of acetylene, lower alkyl lower alkene cyano, phenyl, heterocyclic aromatic, heterocycle, and substituted forms thereof. In a more preferred embodiment, the C-7 substituent is a phenyl or substituted phenyl having the structure ##STR14## wherein aryl substituents at positions C-14 to C-18 taken separately may be selected from the group consisting of hydrogen, chlorine, fluorine, lower alkyl carboxylic acid, sulfonic acid, --CH₂ OH, alkoxy, phenoxy, linking group, and substituted forms thereof. Preferably, the phenyl substituent at C-18 is selected from the group consisting of carboxylic acid and sulfonate, and is most preferably carboxylic acid. In another preferred embodiment, substituents at positions C-14 and C-17 are chlorine. In yet another preferred embodiment, substituents at positions C-14 to C-17 are all chlorine or all fluorine. In a particularly preferred embodiment, substituents at one of positions C-15 and C-16 is linking group and the other is hydrogen, substituents at positions C-14 and C-17 are chlorine, and a substituent at position C-18 is carboxy.

In an additional preferred embodiment, the compound of Formula II comprises a hydrogen radical at the C-7 position, i.e., the C-7 position is unsubstituted.

In yet another preferred embodiment of the invention, the compound of Formula II includes one or more nitrogen substituents. Preferably, such substituents are selected from the group consisting of lower alkyl, lower alkene, lower alkyne, phenyl, aromatic, heterocycle, polycyclic aromatic, water-solubilizing group, linking group, and substituted forms thereof. More preferably, the nitrogen substituents are selected from the group consisting of lower alkyl, phenyl, polycyclic aromatic, and substituted forms thereof, where exemplary substituents include linking group, and water-solubilizing group.

In another preferred embodiment of this second aspect of the invention, the compound of Formula II includes a third bridging group which when taken together with the C-12-bonded nitrogen and the C-11 and C-12 carbons forms a third ring structure having from 5 to 7 members, and/or a fourth bridging group which when taken together with the C-2-bonded nitrogen and the C-2 and C-3 carbons forms a fourth ring structure having from 5 to 7 members. Preferably, one or both of the third and fourth ring structures has six members. More preferably, the six membered ring structure includes one gem disubstituted carbon, wherein the gem substituents are lower alkyl, e.g., methyl.

In another preferred embodiment of the invention, the compound of Formula II includes aryl substituents at one or more of carbons C-1, C-3 through C-6, C-8 through C-11, and C-13. Exemplary aryl substituents include but are not limited to fluorine, chlorine, lower alkyl, lower alkene, lower alkyne, sulfate, sulfonate, sulfone, sulfonamide, sulfoxide, amino, ammonium, amido, nitrile, lower alkoxy, phenoxy, aromatic, phenyl, polycyclic aromatic, water-solubilizing group, heterocycle, and linking group, including substituted forms thereof. In a particularly preferred embodiment, at least one substituent is sulfonate. In another particularly preferred embodiment, the compound of Formula II includes a fused aromatic ring bonded across the C-3 and C4 carbons, the C4 and C5 carbons, the C-9 and C-10 carbons, or the C-10 and C-11 carbons, including substituted forms thereof. Most preferably, the fused aromatic ring is bonded across the C-3 and C-4 carbons and the C-10 and C11 carbons, or across the C-9 and C-10 carbons and the C-4 and C-5 carbons, including substituted forms thereof.

Several exemplary dye compounds according to this second aspect of the invention are shown in FIGS. 7 and 10-13, i.e., compounds 41-47 and 67, 72, 76 and 81.

B. Synthetic Methods

Generally, the dibenzorhodamine dyes of the present invention are synthesized as follows. See FIG. 4. An anhydride derivative 30, e.g., a phthalic anhydride, is mixed with 1-amino-3-methoxy intermediates 31 and 32, and Lewis acid, e.g., ZnCl₂, where the R-substituents in compound 30 may be the same or different, but are preferably the same. Exemplary R-substituents include but are not limited to acetylene, lower alkyl lower alkene, phenyl, heterocycle, and substituted forms thereof. The mixture is heated briefly until melting is observed. A solvent, e.g., 1,2-dichlorobenzene, is added to the reaction mixture, and the heterogeneous mixture is heated to about 130° C. to about 180° C. The crude reaction mixture is cooled and purified by normal phase flash chromatography to yield dye compound 33. When the anhydride is part of a substituted phthalic anhydride, e.g., compound 34, two isomers are formed. See FIG. 5. The isomers 35 and 36 are separated by PTLC. The isomerically pure dyes are identified by single spots on normal and reverse phase TLC and by their UV/Visible absorption spectra and their long wavelength fluorescent excitation and emission spectra.

An alternative procedure for the synthesis of asymmetrical dye compounds is shown in FIG. 6. In this process, an anhydride derivative, e.g., phthalic anhydride 34, is mixed with dry nitrobenzene and heated. The mixture is cooled to room temperature and anhydrous AlCl₃ is added with stirring. Subsequently a 1-amino-3-methoxy intermediate 31 is added with stirring and the reaction is heated. The reaction is cooled and suspended in EtOAc. The organic layer is washed with saturated NH₄ Cl, brine, dried over Na₂ SO₄, filtered, and the solvent removed in vacuo. The resulting ketone intermediates 37/38 are purified and separated into distinct isomers 37 and 38 (except where substituents at C-14 and C-17 are the same and substituents at C-15 and C-16 are the same) by flash chromatography or recrystallization. The methoxy group of the isomerically pure ketone intermediate 37 or 38 is removed according to a general boron tribromide deprotection procedure. Thus, compound 38 gives the amino-hydroxynapthalene ketone intermediate 39. Amino-hydroxynapthalene ketone intermediate 39 is then reacted with a 1-amino-3-methoxy intermediate 32. The reaction is cooled, giving isomerically pure and asymmetrically substituted product 40 that may be further purified by PTLC.

In another method for synthesizing the dibenzorhodamine dyes of the present invention particularly suited to the synthesis of dyes not substituted at the C-7 position, i.e., pyronine dyes, the dyes are synthesized from hydroxybenzoindoline intermediates generated from O-protected N-substituted 3-hydroxybenzoindoline compounds following deprotection of the oxygen protecting group, e.g. methyl group deprotection by ademethylating reagent i.e., aluminum chloride, and isolated by normal phase chromatographic purification. According to the synthesis, a hydroxybenzoindoline intermediate, corresponding to one half of a dye molecule, is first reacted with a formylating reagent, e.g. methylformanilide/POCl₃, and the ensuing formylated hydroxybenzoindoline intermediate is reacted directly with a different (or same) hydroxybenzoindoline intermediate, corresponding to the other half of the dye molecule. The reaction is run under acidic dehydrating conditions, i.e. POCl₃, and heat, i.e 120-160° C. to give the crude carboxylic acid ester derivatized benzopyronine dye. In some cases, the methoxybenzoindoline intermediate is formylated prior to methyl group deprotection and then the methyl group of the formylated methoxyindoline derivative is deprotected to give the formylated hydroxybenzoindoline intermediate prior to reaction with the second equivalent of hydroxyindoline to give the pyronine dye. The pure dye is isolated after aqueous work-up and normal phase chromatography. The intermediate dye carboxylic acid ester is then hydrolysed with acid, i.e. HBr, to give the free acid dye derivatives after aqueous work-up and normal phase chromatography. N-phenyl substituted dyes may be subsequently sulfonated with a sulfonating agent, e.g., ClSO₃ H to give a final preferred dye derivative after aqueous work-up and normal phase chromatography.

V. Energy Transfer Dyes Incorporating the Dibenzorhodamine Dyes

In another aspect, the present invention comprises energy transfer dye compound s incorporating the dibenzorhodamine dye compounds of Formula I. Generally, the energy transfer dyes of the present invention include a donor dye which absorbs light at a first wavelength and emits excitation energy in response, an acceptor dye which is capable of absorbing the excitation energy emitted by the donor dye and fluorescing at a second wavelength in response, and a linker which attaches the donor dye to the acceptor dye, the linker being effective to facilitate efficient energy transfer between the donor and acceptor dyes. A through discussion of the structure, synthesis and use of such energy transfer dyes is provided by Lee et al., U.S. Pat. No. 5,800,996, and Mathies et al., U.S. Pat. No. 5,654,419.

In a preferred embodiment, the linker includes a functional group which gives the linker some degree of structural rigidity, such as an alkene, diene, an alkyne, a five and six membered ring having at least one unsaturated bond or a fused ring structure.

One preferred linker according to the present invention for linking a donor dye to an acceptor dye in an energy transfer fluorescent dye has the general structure ##STR15## where R₂₁ is a lower alkyl attached to the donor dye, Z₁ is either NH, sulfur or oxygen, R₂₂ is a substituent which includes an alkene, diene, alkyne, a five and six membered ring having at least one unsaturated bond or a fused ring structure which is attached to the carbonyl carbon, and R₂₈ includes a functional group which attaches the linker to the acceptor dye.

In one embodiment of this linker, illustrated below, the linker has the general structure ##STR16## where R₂₁ and R₂₂ are as detailed above, Z₁ and Z₂ are each independently either NH, sulfur or oxygen, R₂₉ is a lower alkyl, and the terminal carbonyl group is attached to a ring structure of the acceptor dye. In the variation where Z₂ is nitrogen, the C(O)R₂₂ R₂₉ Z₂ subunit forms an amino acid subunit. Particular examples of five or six membered rings which may be used as R₂₂ in the linker include, but are not limited to cyclopentene, cyclohexene, cyclopentadiene, cyclohexadiene, furan, thiofuran, pyrrole, pyrazole, isoimidazole, pyran, pyrone, benzene, pyridine, pyridazine, pyrimidine, triazine, pyrazine and oxazine. Examples of fused ring structures include, but are not limited to indene, benzofuran, thionaphthene, indole and naphthalene. A preferred embodiment of this linker is where R₂₁ and R₂₉ are methylene, Z₁ and Z₂ are NH, and R₂₂ is benzene, as shown below. ##STR17##

In another preferred embodiment of the energy-transfer-dye aspect of the present invention, the linker attaches to the dibenzorhodamine dye component of the energy transfer dye at the C-1 or 13 positions, or, alternatively, where the C-7 substituent is phenyl or substituted phenyl, at one of the C-15 or C-16 positions. In a particularly preferred embodiment, both members of the energy transfer pair are dibenzorhodamine dyes, and the first member is linked through the C-1 position and the second member is linked through one of the C-15 or C-16 positions.

In yet another preferred embodiment of the energy-transfer-dye aspect of the present invention, a first member the dye pair is a dibenzorhodamine dye, and a second member of the dye pair is cyanine, phthalocyanine, squaraine, bodipy, fluorescein, or dibenzorhodamine dye having different substitutions than the first member.

VI. Reagents Incorporating the Dibenzorhodamine Dyes

In another aspect, the present invention comprises reagents labeled with the dibenzorhodamine dye compounds of Formula I. Reagents of the invention can be virtually anything to which the dyes of the invention can be attached. Preferably, the dye is covalently attached to the reagent. Reagents may include but are not limited to proteins, polypeptides, polysaccharides, nucleotides, nucleosides, polynucleotides, lipids, solid supports, organic and inorganic polymers, and combinations and assemblages thereof such as chromosomes, nuclei, living cells, such as bacteria or other microorganisms, mammalian cells, tissues, and the like.

A. Nucleoside/tide Reagents

A preferred class of labeled reagents comprise nucleoside/tides that incorporate the dibenzorhodamine dyes of the invention. Such nucleoside/tide reagents are particularly useful in the context of labeling polynucleotides formed by enzymatic synthesis, e.g., nucleotide triphosphates used in the context of PCR amplification, Sanger-type polynucleotide sequencing, and nick-translation reactions.

Generally, the structure of the labeled nucleoside/tide reagent is

    NUC--D                                                     FORMULA III

where NUC is a nucleoside/tide or nucleoside/tide analog and D is a dibenzorhodamine dye compound of Formula II.

The linkage linking the nucleoside/tide and the dye may be attached to the dye at any one of substituent positions C-1 to C-18 or at a C-2 bonded nitrogen or a C-12 bonded nitrogen. Preferably, the dye includes a phenyl or substituted phenyl substituent at the C-7 position and is attached to the nucleoside/tide at one of the C-15 or C-16 substituent positions, the other position being a hydrogen atom.

When NUC includes a purine base, the linkage between NUC and D is attached to the N⁸ -position of the purine, when NUC includes a 7-deazapurine base, the linkage is attached to the N⁷ -position of the 7-deazapurine, and when NUC includes a pyrimidine base, the linkage is attached to the N⁵ -position of the pyrimidine.

Nucleoside labeling can be accomplished using any one of a large number of known nucleoside/tide labeling techniques employing known linkages, linking groups, and associated complementary functionalities. Generally, the linkage linking the dye and nucleoside should (i) not interfere with oligonucleotide-target hybridization, (ii) be compatible with relevant enzymes, e.g., polymerases, ligases, and the like, and (iii) not adversely affect the fluorescence properties of the dye. Exemplary base labeling procedures suitable for use in connection with the present invention include the following: Gibson et al, Nucleic Acids Research, 15:6455-6467 (1987); Gebeyehu et al, Nucleic Acids Research, 15: 4513-4535 (1987); Haralambidis et al, Nucleic Acids Research, 15: 4856-4876 (1987); Nelson et al., Nucleosides and Nucleotides, 5(3): 233-241 (1986); Bergstrom, et al., JACS, 111: 374-375 (1989); and U.S. Pat. Nos. 4,855,225, 5,231,191, and 5,449,767.

Preferably, the linkages are acetylenic amido or alkenic amido linkages, the linkage between the dye and the nucleoside/tide base being formed by reacting an activated N-hydroxysuccinimide (NHS) ester of the dye with an alkynylamino- or alkenylamino-derivatized base of a nucleoside/tide. More preferably, the resulting linkage is 3-(carboxy)amino-1-propyn-1-yl having the structure ##STR18##

Alternative preferred linkages include substituted propargylethoxyamido linkages having the structure

    NUC--C.tbd.C--CH.sub.2 OCH.sub.2 CH.sub.2 NR.sub.3 X--D

wherein X is selected from the group consisting of ##STR19## where n ranges from 1 to 5, ##STR20## where n ranges from 1 to 5, ##STR21## R₁ is selected from the group consisting of --H, lower alkyl and protecting group; and R₃ is selected from the group consisting of --H and lower alkyl. See Khan et al., U.S. patent application Ser. No. 08/833,854 filed Apr. 10, 1997.

The synthesis of alkynylamino-derivatized nucleosides is taught by Hobbs et al. in European Patent Application No. 87305844.0, and Hobbs et al., J. Org. Chem., 54: 3420 (1989). Briefly, the alkynylamino-derivatized nucleotides are formed by placing the appropriate halodideoxynucleoside (usually 5-iodopyrimidine and 7-iodo-7-deazapurine dideoxynucleosides as taught by Hobbs et al. (cited above)) and Cu(I) in a flask, flushing with argon to remove air, adding dry DMF, followed by addition of an alkynylamine, triethyl-amine and Pd(0). The reaction mixture is stirred for several hours, or until thin layer chromatography indicates consumption of the halodideoxynucleoside. When an unprotected alkynylamine is used, the alkynylamino-nucleoside can be isolated by concentrating the reaction mixture and chromatographing on silica gel using an eluting solvent which contains ammonium hydroxide to neutralize the hydrohalide generated in the coupling reaction. When a protected alkynylamine is used, methanol/methylene chloride can be added to the reaction mixture, followed by the bicarbonate form of a strongly basic anion exchange resin. The slurry can then be stirred for about 45 minutes, filtered, and the resin rinsed with additional methanol/methylene chloride. The combined filtrates can be concentrated and purified by flash-chromatography on silica gel using a methanol-methylene chloride gradient. The triphosphates are obtained by standard techniques.

Particularly preferred nucleosides/tides of the present invention are shown below in Formula IV wherein ##STR22## B is a nucleoside/tide base, e.g., uracil, cytosine, deazaadenine, or deazaguanosine; W₁ and W₂ taken separately are OH or a group capable of blocking polymerase-mediated template-directed polymerzation, e.g., H, fluorine and the like; W₃ is OH, or mono-, di- or triphosphate or phosphate analog; and D is a dye compound of Formula I. In one particularly preferred embodiment, the nucleotides of the present invention are dideoxynucleotide triphosphates having the structure shown in Formula IV.1 below, including associated counterions if present. ##STR23## Labeled dideoxy nucleotides such as that shown in Formula IV.1 find particular application as chain terminating agents in Sanger-type DNA sequencing methods utilizing fluorescent detection.

In a second particularly preferred embodiment, the nucleotides of the present invention are deoxynucleotide triphosphates having the structure shown in Formula IV.2 below. ##STR24## Labeled deoxynucleotides such as that shown in Formula IV.2 find particular application as reagents for labeling polymerase extension products, e.g., in the polymerase chain reaction or nick-translation.

B. Polynucleotide Reagents

Yet another preferred class of reagents of the present invention comprise polynucleotides labeled with the dibenzorhodamine dyes of the invention. Such labeled polynucleotides are useful in a number of important contexts including as DNA sequencing primers, PCR primers, oligonucleotide hybridization probes, oligonucleotide ligation probes, and the like.

In one preferred embodiment, the labeled polynucleotides of the present invention include multiple dyes located such that fluorescence energy transfer takes place between a donor dye and an acceptor dye. Such multi-dye energy-transfer polynucleotides find application as spectrally-tunable sequencing primers, e.g., Ju et al., Proc. Natl. Acad Sci. USA 92: 43474351 (1995), and as hybridization probes, e.g., Lee et al. Nucleic Acids Research, 21: 3761-3766 (1993).

Labeled polynucleotides may be synthesized either enzymatically, e.g., using a DNA polymerase or ligase, e.g., Stryer, Biochemistry, Chapter 24, W.H. Freeman and Company (1981), or by chemical synthesis, e.g., by the phosphoramidite method, the phosphite-triester method, and the like, e.g., Gait, Oligonucleotide Synthesis, IRL Press (1990). Labels may be introduced during enzymatic synthesis utilizing labeled nucleotide triphosphate monomers as described above, or introduced during chemical synthesis using labeled non-nucleotide or nucleotide phosphoramidites as described above, or may be introduced subsequent to synthesis.

Generally, if the labeled polynucleotide is made using enzymatic synthesis, the following procedure may be used. A template DNA is denatured and an oligonucleotide primer is annealed to the template DNA. A mixture of deoxynucleotide triphosphates is added to the mixture including dGTP, dATP, dCTP, and dTTP where at least a fraction of the deoxynucleotides is labeled with a dye compound of the invention as described above. Next, a polymerase enzyme is added under conditions where the polymerase enzyme is active. A labeled polynucleotide is formed by the incorporation of the labeled deoxynucleotides during polymerase-mediated strand synthesis. In an alternative enzymatic synthesis method, two primers are used instead of one, one primer complementary to the + strand and the other complementary to the - strand of the target, the polymerase is a thermostable polymerase, and the reaction temperature is cycled between a denaturation temperature and an extension temperature, thereby exponentially synthesizing a labeled complement to the target sequence by PCR, e.g., PCR Protocols, Innis et al. eds., Academic Press (1990).

Labeled polynucleotides may be chemically synthesized using the phosphoramidite method. Detailed descriptions of the chemistry used to form polynucleotides by the phosphoramidite method are provided elsewhere, e.g., Caruthers et al., U.S. Pat. Nos. 4,458,066 and 4,415,732; Caruthers et al., Genetic Engineering, 4: 1-17 (1982); Users Manual Model 392 and 394 Polynucleotide Synthesizers, pages 6-1 through 6-22, Applied Biosystems, Part No. 901237 (1991).

The phosphoramidite method of polynucleotide synthesis is the preferred method because of its efficient and rapid coupling and the stability of the starting materials. The synthesis is performed with the growing polynucleotide chain attached to a solid support, so that excess reagents, which are in the liquid phase, can be easily removed by filtration, thereby eliminating the need for purification steps between synthesis cycles.

The following briefly describes the steps of a typical polynucleotide synthesis cycle using the phosphoramidite method. First, a solid support including a protected nucleotide monomer is treated with acid, e.g., trichloroacetic acid, to remove a 5'-hydroxyl protecting group, freeing the hydroxyl for a subsequent coupling reaction. An activated intermediate is then formed by simultaneously adding a protected phosphoramidite nucleoside monomer and a weak acid, e.g., tetrazole, to the reaction. The weak acid protonates the nitrogen of the phosphoramidite forming a reactive intermediate. Nucleoside addition is complete within 30 s. Next, a capping step is performed which terminates any polynucleotide chains that did not undergo nucleoside addition. Capping is preferably done with acetic anhydride and 1-methylimidazole. The internucleotide linkage is then converted from the phosphite to the more stable phosphotriester by oxidation using iodine as the preferred oxidizing agent and water as the oxygen donor. After oxidation, the hydroxyl protecting group is removed with a protic acid, e.g., trichloroacetic acid or dichloroacetic acid, and the cycle is repeated until chain elongation is complete. After synthesis, the polynucleotide chain is cleaved from the support using a base, e.g., ammonium hydroxide or t-butyl amine. The cleavage reaction also removes any phosphate protecting groups, e.g., cyanoethyl. Finally, the protecting groups on the exocyclic amines of the bases and the hydroxyl protecting groups on the dyes are removed by treating the polynucleotide solution in base at an elevated temperature, e.g., 55° C.

Any of the phosphoramidite nucleoside monomers may be dye-labeled phosphoramidites as described above. If the 5'-terminal position of the nucleotide is labeled, a labeled non-nucleotidic phosphoramidite of the invention may be used during the final condensation step. If an internal position of the oligonucleotide is labeled, a labeled nucleotidic phosphoramidite of the invention may be used during any of the condensation steps.

Subsequent to synthesis, the polynucleotide may be labeled at a number of positions including the 5'-terminus, e.g., Oligonucleotides and Analogs, Eckstein ed., Chapter 8, IRL Press (1991) and Orgel et al., Nucleic Acids Research 11(18): 6513 (1983); U.S. Pat. No. 5,118,800; the phosphodiester backbone, e.g., ibid., Chapter 9; or at the 3'-terminus, e.g., Nelson, Nucleic Acids Research 20(23): 6253-6259, and U.S. Pat. Nos. 5,401,837 and 5,141,813. For a through review of oligonucleotide labeling procedures see R. Haugland in Excited States of Biopolymers, Steiner ed., Plenum Press, New York (1983).

As shown in FIGS. 14 and 15, in one preferred post-synthesis chemical labeling method an oligonuleotide is labeled as follows. A dye including a carboxy linking group is converted to the N-hydroxysuccinimide ester by reacting with approximately 1 equivalent of 1,3-dicyclohexylcarbodiimide and approximately 3 equivalents of N-hydroxysuccinimide in dry ethyl acetate for 3 hours at room temperature. The reaction mixture is washed with 5% HCl, dried over magnesium sulfate, filtered, and concentrated to a solid which is resuspended in DMSO. The DMSO dye stock is then added in excess (10-20 ×) to an aminohexyl derivatized oligonucleotide in 0.25 M bicarbonate/carbonate buffer at pH 9.4 and allowed to react for 6 hours, e.g., U.S. Pat. No. 4,757,141. The dye labeled oligonucleotide is separated from unreacted dye by passage through a size-exclusion chromatography column eluting with buffer, e.g., 0.1 molar triethylamine acetate (TEAA). The fraction containing the crude labeled oligonucleotide is further purified by reverse phase HPLC employing gradient elution.

VII. Methods Utilizing the Dibenzorhodamine Dyes

The dyes and reagents of the present invention are well suited to any method utilizing fluorescent detection, particularly methods requiring the simultaneous detection of multiple spatially-overlapping analytes. Dyes and reagents of the invention are particularly well suited for identifying classes of polynucleotides that have been subjected to a biochemical separation procedure, such as electrophoresis, or that have been distributed among locations in a spatially-addressable hybridization array.

In a preferred category of methods referred to herein as "fragment analysis" or "genetic analysis" methods, labeled polynucleotide fragments are generated through template-directed enzymatic synthesis using labeled primers or nucleotides, e.g., by ligation or polymerase-directed primer extension; the fragments are subjected to a size-dependent separation process, e.g., electrophoresis or chromatography; and, the separated fragments are detected subsequent to the separation, e.g., by laser-induced fluorescence. In a particularly preferred embodiment, multiple classes of polynucleotides are separated simultaneously and the different classes are distinguished by spectrally resolvable labels.

One such fragment analysis method known as amplified fragment length polymorphisim detection (AmpFLP) is based on amplified fragment length polymorphisms, i.e., restriction fragment length polymorphisms that are amplified by PCR- These amplified fragments of varying size serve as linked markers for following mutant genes through families. The closer the amplified fragment is to the mutant gene on the chromosome, the higher the linkage correlation. Because genes for many genetic disorders have not been identified, these linkage markers serve to help evaluate disease risk or paternity. In the AmpFLPs technique, the polynucleotides may be labeled by using a labeled polynucleotide PCR primer, or by utilizing labeled nucleotide triphosphates in the PCR.

In another such fragment analysis method known as nick translation, a reaction is used to replace unlabeled nucleoside triphosphates in a double-stranded DNA molecule with labeled ones. Free 3'-hydroxyl groups are created within the unlabeled DNA by "nicks" caused by deoxyribonuclease I (DNAase I) treatment. DNA polymerase I then catalyzes the addition of a labeled nucleotide to the 3'-hydroxyl terminus of the nick. At the same time, the 5' to 3'-exonuclease activity of this enzyme eliminates the nucleotide unit from the 5'-phosphoryl terminus of the nick. A new nucleotide with a free 3'-OH group is incorporated at the position of the original excised nucleotide, and the nick is shifted along by one nucleotide unit in the 3' direction. This 3' shift will result in the sequential addition of new labeled nucleotides to the DNA with the removal of existing unlabeled nucleotides. The nick-translated polynucleotide is then analyzed using a separation process, e.g., electrophoresis.

Another exemplary fragment analysis method is based on variable number of tandem repeats, or VNTRs. VNTRs are regions of double-stranded DNA that contain adjacent multiple copies of a particular sequence, with the number of repeating units being variable. Examples of VNTR loci are pYNZ22, pMCT118, and Apo B. A subset of VNTR methods are those methods based on the detection of microsatellite repeats, or short tandem repeats (STRs), i.e., tandem repeats of DNA characterized by a short (2-4 bases) repeated sequence. One of the most abundant interspersed repetitive DNA families in humans is the (dC-dA)n-(dG-dT)n dinucleotide repeat family (also called the (CA)n dinucleotide repeat family). There are thought to be as many as 50,000 to 100,000 (CA)n repeat regions in the human genome, typically with 15-30 repeats per block. Many of these repeat regions are polymorphic in length and can therefore serve as useful genetic markers. Preferably, in VNTR or STR methods, label is introduced into the polynucleotide fragments by using a dye-labeled PCR primer.

In a particularly preferred fragment analysis method, classes identified in accordance with the invention are defined in terms of terminal nucleotides so that a correspondence is established between the four possible terminal bases and the members of a set of spectrally resolvable dyes. Such sets are readily assembled from the dyes of the invention by measuring emission and absorption bandwidths with commercially available spectrophotometers. More preferably, the classes arise in the context of the chemical or chain termination methods of DNA sequencing, and most preferably the classes arise in the context of the chain termination methods, i.e., dideoxy DNA sequencing, or Sanger-type sequencing.

Sanger-type sequencing involves the synthesis of a DNA strand by a DNA polymerase in vitro using a single-stranded or double-stranded DNA template whose sequence is to be determined. Synthesis is initiated at a defined site based on where an oligonucleotide primer anneals to the template. The synthesis reaction is terminated by incorporation of a nucleotide analog that will not support continued DNA elongation. Exemplary chain-terminating nucleotide analogs include the 2',3'-dideoxynucleoside 5'-triphosphates (ddNTPs) which lack the 3'-OH group necessary for 3' to 5' DNA chain elongation. When proper proportions of dNPs (2'-deoxynucleoside 5-triphosphates) and one of the four ddNTPs are used, enzyme-catalyzed polymerization will be terminated in a fraction of the population of chains at each site where the ddNTP is incorporated. If labeled primers or labeled ddNTPs are used for each reaction, the sequence information can be detected by fluorescence after separation by high-resolution electrophoresis. In the chain termination method, dyes of the invention can be attached to either sequencing primers or dideoxynucleotides. Dyes can be linked to a complementary functionality on the 5'-end of the primer, e.g. following the teaching in Fung et al, U.S. Pat. No. 4,757,141; on the base of a primer; or on the base of a dideoxynucleotide, e.g. via the alkynylamino linking groups disclosed by Hobbs et al, supra.

In each of the above fragment analysis methods labeled polynucleotides are preferably separated by electrophoretic procedures, e.g. Gould and Matthews, cited above; Rickwood and Hames, Eds., Gel Electrophoresis of Nucleic Acids: A Practical Approach, IRL Press Limited, London, 1981; Osterman, Methods of Protein and Nucleic Acid Research, Vol. 1 Springer-Verlag, Berlin, 1984; or U.S. Pat. Nos. 5,374,527, 5,624,800 and/or 5,552,028. Preferably the type of electrophoretic matrix is crosslinked or uncrosslinked polyacrylamide having a concentration (weight to volume) of between about 2-20 weight percent. More preferably, the polyacrylamide concentration is between about 4-8 percent. Preferably in the context of DNA sequencing in particular, the electrophoresis matrix includes a denaturing agent, e.g., urea, formamide, and the like. Detailed procedures for constructing such matrices are given by Maniatis et al., "Fractionation of Low Molecular Weight DNA and RNA in Polyacrylamide Gels Containing 98% Formamide or 7 M Urea," in Methods in Enzymology, 65: 299-305 (1980); Maniatis et al., "Chain Length Determination of Small Double- and Single-Stranded DNA Molecules by Polyacrylamide Gel Electrophoresis," Biochemistry, 14: 3787-3794 (1975); Maniatis et al., Molecular Cloning. A Laboratory Manual, Cold Spring Harbor Laboratory, New York, pgs. 179-185 (1982); and ABI PRISM™ 377 DNA Sequencer User's Manual, Rev. A, January 1995, Chapter 2 (p/n 903433, The Perkin-Elmer Corporation, Foster City, Calif.). The optimal electrophoresis conditions, e.g., polymer concentration, pH, temperature, concentration of denaturing agent, employed in a particular separation depends on many factors, including the size range of the nucleic acids to be separated, their base compositions, whether they are single stranded or double stranded, and the nature of the classes for which information is sought by electrophoresis. Accordingly application of the invention may require standard preliminary testing to optimize conditions for particular separations.

Subsequent to electrophoretic separation, the dye-polynucleotide conjugates are detected by measuring the fluorescence emission from the dye labeled polynucleotides. To perform such detection, the labeled polynucleotides are illuminated by standard means, e.g. high intensity mercury vapor lamps, lasers, or the like. Preferably the illumination means is a laser having an illumination beam at a wavelength above about 600 nm. More preferably, the dye-polynucleotides are illuminated by laser light generated by a He--Ne gas laser or a solid-state diode laser. The fluorescence is then detected by a light-sensitive detector, e.g., a photomultiplier tube, a charged coupled device, or the like. Exemplary electrophoresis detection systems are described elsewhere, e.g., U.S. Pat. Nos. 5,543,026; 5,274,240; 4,879,012; 5,091,652 and 4,811,218.

VIII. EXAMPLES

The invention will be further clarified by a consideration of the following examples, which are intended to be purely exemplary of the invention and not to in any way limit its scope.

Materials and Methods

All chemicals were purchased from Aldrich Chemical Company unless otherwise noted. Martius yellow was purchased from Fluka. Acetone was dried over CaSO₄ and distilled. Dichloromethane (CH₂ Cl₂) and nitrobenzene were dried over CaH₂ and distilled. Tetrahydrofuran (THF) was dried over LAH and distilled as needed. Triethylamine (Et₃ N) was dried over sodium and distilled. DMSO (99.9%) and N,N-diisopropylethylamine (99.5%) were dried and stored over activated molecular sieves. Silica gel (220-400 mesh) from VWR was used for normal phase flash chromatography. Reverse phase chromatography was performed on octadecyl functionalized silica gel from Aldrich. Preparative thin layer chromatography (PTLC) was performed on 1 and 2 mm pre-made silica gel plates from EM science (VWR). TLC was performed on aluminum back silica gel 60 plates from EM science (VWR). Developed spots were visualized with both long and short wavelength UV irradiation.

Absorption spectroscopy was performed on a Hewlett Packard model 8451A UV/Vis diode array spectrophotometer. Fluorescence measurements were made on a Perkin-Elmer LS-50B luminescence spectrophotometer. NMR spectra were determined on a Varian 300 MHz NMR referenced relative to a solvent peak at 7.26 ppm in CD₃ Cl or 3.31 ppm in CD₃ OD. HPLC purification of oligomer labeled dye fragments was performed on a Perkin-Elmer Series 200 pump, employing a reverse phase C-18 column, with both UV and fluorescence emission detection. Fluorescence detection was performed by a Perkin-Elmer LC 240 fluorescence detector equipped with a red sensitive PMT, and UV detection was performed with a Model LC 295 UV/Vis detector. Pump and detectors were all interfaced with a Perkin-Elmer Model 1022 computer run in two-channel mode. Buffers were made up fresh from the following concentrated stock: 10×TBE (0.89 M tris-(hydroxymethyl)aminomethane, 0.89 M borate, 0.02 M ethylenediaminetetraacetic acid disodium salt), and 0.1 M TEAA (triethylamine acetate).

All reactions were run in an oven-dried round bottom flask, under argon atmosphere, and capped with a rubber septum. Anhydrous solvents were manipulated under an argon atmosphere with oven-dried syringes. As used herein, the term "aqueous workup" refers to a purification method comprising the following steps: (i) adding a reaction mixture to a saturated aqueous NH₄ Cl solution, a 5% HCl solution, or a saturated Na₂ S₂ O₃ solution, (ii) extracting the solution three times with an organic solvent, e.g., EtOAc, or CH₂ Cl₂, (iii) washing the combined organic layer once with saturated NaCl, (iv) drying the solution with Na₂ SO₄, (v) filtering the drying agent, and (vi) removing the solvent in vacuo. 3-Methoxy-1-hydroxynapthalene 1 was synthesized from 1,3-dihydroxynapthalene by the method of K. H. Bell and L. F. McCaffery (Aust. J. Chem. 46: 731 (1993)). 1-Amino-3-methoxynapthalene 18 was synthesized according the procedure of G. T. Morgan and E. D. Evans (J. Chem. Soc. 115: 1126 (1919)), or, as described below in Example 10.

Example 1 Synthesis of 1-Diethylamino-3-Hydroxynapthalene 4 (FIG. 1)

3-methoxy-1-hydroxy napthalene 1 (1 gm) was suspended in dry CH₂ Cl₂ (30 mL). Dry triethylamine (1.2 equivalents) was added and the reaction was cooled to -5° C. Trifluoromethanesulfonic anhydride (1.1 equivalents) suspended in CH₂ Cl₂ (15 mL) was added dropwise with vigorous stirring over a period of 2 hours. The reaction was allowed to come to room temperature and subjected to aqueous work up using 5% HCl and CH₂ Cl₂. The resulting crude 3-methoxynapthalene-1-triflate 2 was purified by normal phase flash chromatography employing an EtOAc/Hexane (1:10) mobile phase.

The purified 3-methoxynapthalene-1-triflate 2 was converted to the 1-diethylamino-3-methoxynapthalene 3 using the palladium-catalyzed triflate/amine coupling procedure of Wolfe as follows (J. P. Wolfe and S. L. Buchwald, JOC, 61: 1133 (1996)). The 3-methoxy-napthalene-1-triflate 2 (1 gram) was suspended in 100 mL of dry toluene with 0.015 equivalents of (S)-(-)-2,2'-bis(diphenylphosphino)-1,1'-binapthyl (BINAP), 0.005 equivalents of tris(dibenzylideneacetone)dipalladium Pd₂ (dba)₃), and 3 equivalents of dry diethyl amine. The reaction was purged with argon, and 3.3 equivalents of solid sodium t-butoxide was added with stirring. The reaction was then heated, and stirred for 16 hours at 80° C. in an oil bath. The reaction was allowed to come to room temperature and subjected to aqueous work up using 5% HCl and CH₂ Cl₂ resulting in a crude 1-diethylamino-3-methoxynapthalene 3, which was purified by normal phase flash chromatography employing EtOAc: hexane (1:49) as the mobile phase (¹ HNMR: CD₃ Cl d 8.20 (broad d, 1H, J=9 Hz), 7.72(broad d, 1H, J=7.8 Hz), 7.43 (dt, 1H, J=7.2, 1.2 Hz), 7.34 (dt, 1 H, J=7.7, 1.2 Hz), 6.88 (d, 1H, J=2.4 Hz), ), 6.82 (d, 1H, J=2.4 Hz), 3.93 (s, 3H), 3.21 (q, 4H, J=1.08 (t, 6H J=7.2 Hz)).

Next, the methyl group of the 1-diethyl-amino-3-methoxy-napthalene 3 was removed by boron tribromide deprotection as follows. The 1-amino-3-methoxy-napthalene (100 mg) was suspended in dry CH₂ Cl₂ (5 mL) and the mixture was cooled to -70° C. in a dry ice/acetone bath. Boron tribromide (10 equivalents) was added dropwise and the reaction was stirred for 30 minutes, then placed in a refrigerator (0° C.) overnight. The reaction was quenched at -70° C. by careful addition of MeOH (10 mL). Solid NaHCO₃ (30 equivalents) was added and the reaction was warmed to room temperature, then briefly heated to reflux. The mixture was cooled and filtered, the filtrate was acidified with AcOH, and the solvent was removed in vacuo to give the crude 1-diethylamino-3-hydroxynapthalene 4, which was purified by normal phase flash chromatography employing EtOAc: hexane (1:4) as the mobile phase.

Example 2 Synthesis of N-Phenyl-3,3-Dimethyl-Hydroxy-Benzoindoline 9 (FIG. 1)

The 3-methoxynapthalene-1-triflate 2 was derivatized with aniline according to the palladium catalyzed triflate/amine coupling reaction described above in Example 1 to give the 1-anilino-3-methoxynapthalene 5.

The 1-anilino-3-methoxynapthalene 5 was acetylated by an amino group acetylation procedure as follows. The 1-amino-3-methoxynapthalene 5 (500 mg) and 1.2 equivalents of dry Et₃ N were suspended in 10 mL of dry CH₂ Cl₂ and cooled to -5° C. using an ice/NaCl bath. 1.1 equivalent of 2-bromo-2-methylpropionylchloride was added dropwise and the reaction was stirred for 1 hour at -5° C. and stirred at room temperature for an additional 1 hour. The reaction was allowed to come to room temperature and subjected to aqueous work up using 5% HCl and EtOAc resulting in the crude intermediate 1-(bromoalkyl)amido-3-methoxy-napthalene 6, which was purified by normal phase flash chromatography employing EtOAc: hexane (1:9) as the mobile phase.

The 1-(bromoalkyl)amido-3-methoxy-napthalene 6 was cyclized using an AlCl₃ catalyzed Friedel-Crafts cyclization procedure as follows. 1 to 3 equivalents of AlCl₃ in nitrobenzene was added to the 1-(bromoalkyl)amido-3-hydroxy-napthalene 6. The reaction was heated to 130° C. and reacted for 1 hour. Aqueous work-up using NH₄ Cl and EtOAc gave the crude N-phenyl-benzoindolinone intermediate 7, which was purified by normal phase flash chromatography employing EtOAc: hexane (1:4) as the mobile phase. The amide carbonyl group of the N-phenyl-benzoindoline intermediate 7 was then reduced with LAH to give compound 8 (¹ HNMR: CD₃ Cl d 7.71 (d, 1H. J=7.8 Hz), 7.32 (m, 2H), 7.24 (m, 2H), 7.07 (bt, 1H, J=6.6 Hz), 6.96 (m, 3H), 6.84 (s, 1H), 3.97 (s, 3H), 3.92 (s, 2H), 1.44 (s, 6H).

Methoxy group deprotection of compound 8 was effected using the boron tribromide deprotection procedure described in Example 1, resulting in the N-phenyl-3,3-dimethyl-hydroxy-benzoindoline 9.

Example 3 Synthesis of N-Methyl-5-Hydroxy-(Tetrahydro)benzoquinoline 15 (FIG. 2)

Compound 10 was synthesized by condensation of methoxy-napthaldehyde and malonic acid employing piperidine catalysis in pyridine. Compound 10 was reduced with hydrogen over 10% Pd/carbon, followed by LAH reduction, and reacted as outlined for the synthesis of compound 2 above with trifluoromethanesulfonic anhydride to give the triflate 11. Triflate 11 was then reacted with NaN₃ (3 equiv.) in DMF at 100° C. for 6 hours. Then, the reaction was allowed to come to room temperature and subjected to aqueous work up using pure water and EtOAc resulting in pure compound 12. Compound 12 was suspended in dry CH₂ Cl₂, complexed with 3 to 5 equivalents of solid AlCl₃, and refluxed for 2 hours yielding compound 13.

Compound 13 was alkylated with MeI according to a general amino group alkylation procedure as follows. The 3-methoxybenzoquinoline derivative (100 mg) 13 was suspended in 5 mL of dry THF and cooled to -5° C. (ice/NaCl). 1.1 equivalents of n-butyl lithium (1 M) was added dropwise, and the reaction was stirred for 1 hour. 3 equivalents of the MeI alkylating agent was added slowly and the reaction was allowed to stir at room temperature for 2 hours. Aqueous work-up using NH₄ Cl and EtOAc gave a crude alkylated 3-methoxybenzoquinoline intermediate 14. Intermediate 14 was then purified by normal phase flash chromatography employing EtOAc: hexane (1:19) as the mobile phase (¹ HNMR: CD₃ Cl d 8.1 (broad d, 1H, J=8.1 Hz), 7.68(dd, 1H J=8.1, 1.8 Hz), 7.34 (m, 2H), 6.8 (s, 1H), 3.92 (s, 3H), 3.21 (m, 2H), 2.94 (s, 3H), 2.77 (t, 2H, J=6.6 Hz), 1.92 (m, 2H)). Subsequent methoxy group deprotection by the general boron tribromide procedure described above in Example 1 resulted in the N-methyl-hydroxybenzoquinoline derivative 15.

Example 4 Synthesis of 3-(5-Hydroxybenzoquinolin-1-yl) propanesulfonic acid 17 (FIG. 2)

Compound 13 was synthesized according to the procedure outlined above in Example 3 for the synthesis of the N-methyl-hydroxybenzoquinoline derivative 15. Compound 13 was then alkylated according to the general amino group alkylation procedure described above in Example 3, this time using 1,3-propane sultone as the alkylating agent rather than MeI, to give a 5-methoxybenzoquinoline-N-propanesulfonic acid intermediate 16 (¹ HNMR: CD₃ OD d 7.94 (d, 1H, J=8.7 Hz), 7.65 (d, 1H, J=8.4 Hz), 7.32 (t, 1H), 7.27 (t, 1H), 6.85 (s, 1H), 4.89 (s, 3H), 3.20 (m, 2H), 3.08 (bt, 2H, J=6 Hz), 2.91 (m, 2H), 2.72 (t, 2H, J=6.6 Hz), 2.33 (m, 2H), 1.89 (m, 2H). Subsequent methoxy group deprotection of compound 16 by the general boron tribromide procedure described above in Example 1 resulted in the 3-(5-hydroxybenzoquinolin-1-yl) propanesulfonic acid 17.

Example 5 Synthesis of N-Methyl-2,2,4-Trimethyl-5-Hydroxy-(Tetrahydro)benzoquinoline 22 (FIG. 3)

Following the procedure of A. Rosowsky and E. J. Modest (J.O.C., 30: 1832 (1965)), 1-amino-3-methoxynapthalene 18 (1 gm) was dissolved in dry acetone (50 mL), and 0.01 equivalent of iodine was added to the solution. The reaction was heated and stirred for 16 hours, cooled, and then quenched with saturated Na₂ S₂ O₃. The reaction mixture was then subjected to aqueous work up using saturated Na₂ S₂ O₃ and EtOAc resulting in the crude methoxybenzoquinoline 19. The methoxybenzoquinoline 19 was purified by flash chromatography using an EtOAc/hexane 1:9 mobile phase. Compound 19 was then alkylated with MeI according to the general amino group alkylation procedure described above in Example 3 to give compound 20. Compound 20 was reduced with H₂ in a Parr hydrogenator at 70 psi and 10% Pd/C catalysis to give a N-methyl-2,2,4-trimethyl-5-methoxybenzoquinoline intermediate 21 (¹ HNMR: CD₃ Cl d 8.20 (bd, 1H, J=7.5 Hz), 7.65 (bd, 1H, J=7.5 Hz), 7.33 (m, 2H), 6.89 (s, 1H), 3.94 (s, 3H), 3.14 (b sextet, 1H, J=6.6 Hz), 2.80 (3, 3H), 1.89 (d, 2H, J=8.7), 1.42 (d, 3H, J=6.9 Hz), 1.34 (s, 3H), 1.05 (s, 3H). Subsequent methoxy group deprotection of compound 21 by the general boron tribromide procedure described above in Example 1 gave the N-methyl-5-hydroxy-(tetrahydro)benzoquinoline 22.

Example 6 Synthesis of N-Methyl-3,3-Dimethyl-4-Hydroxy-Benzoindoline 27 (FIG. 3)

1-Amino-3-methoxynapthalene 18 was acetylated with 2-bromo-2-methylpropionyl chloride according to the general amino group acylation procedure described above in Example 2 to give compound 23. Compound 23 was cyclized by the Friedel-Crafts cyclization procedure described above in Example 2 to give compound 24. Next, compound 24 was reduced with 3 equivalents LAH in THF to give the 4-methoxybenzoindoline 25. Compound 25 was alkylated using the general amino group alkylation procedure described above in Example 3 using methyl iodide as the alkylating agent to give a N-methyl-3,3-dimethyl-4-methoxybenzoindoline intermediate 26 (¹ HNMR: CD₃ Cl d 8.07 (bd, 1H, J=8.4 Hz), 7.69 (bd, 1H, J=8.1 Hz), 7.33 (bt, 1H, J=7.8 Hz), 7.22 (bt, 1H, J=8.1 Hz), 6.70 (s, 1H), 3.92 (s, 3H), 3.32 (s, 2H), 3.32 (s, 3H), 1.44 (s, 6H). Subsequent methoxy group deprotection of compound 26 by the general boron tribromide procedure described in Example 1 resulted in the N-methyl-3,3-dimethyl-4-hydroxy-benzoindoline 27.

Example 7 Synthesis of N-Ethyl-3,3-Dimethyl-4-Hydroxy-Benzoindoline 29 (FIG. 3)

The 4-methoxybenzoindoline 25 was synthesized as described above in Example 6. Compound 25 was alkylated by the general amino group alkylation procedure described in Example 3 employing ethyl iodide as the alkylating agent to give the N-ethyl-3,3-dimethyl-4-methoxybenzoindoline intermediate 28 (1HNMR: CD₃ Cl d 7.90 (d, 1H, J=8.7 Hz), 7.68 (d, 1H, J=8.1 Hz), 7.32 (bt, 1H, J=7.5 Hz), 7.22 (bt, 1H, J=6.9 Hz), 6.69 (s, 1H), 3.83 (s, 3H), 3.52 (q, 2H J=7.5 Hz), 3.38 (s, 2H), 1.46 (s, 6H), 1.27 (t, 3H, J=7.5 Hz). Subsequent methoxy group deprotection of compound 28 by the general boron tribromide procedure described in Example 1 yielded the N-ethyl-3,3-dimethyl-4-hydroxy-benzoindoline 29.

Example 8 Synthesis of Selected Dibenzorhodamine Dye Compounds

General Procedure A (FIG. 5). A solid phthalic anhydride derivative 34 was mixed with 1.4 equivalents of an aminohydroxy intermediate 31 and 2.8 equivalents of ZnCl₂. The oven dried reaction vessel was capped with a rubber septa and purged with Argon. The solid mixture was heated briefly at 130° C. until melting was observed, e.g., after approximately 15 minutes. 1,2-Dichlorobenzene (approximately 10 equivalents) was added by syringe to the reaction mixture, and the heterogeneous mixture was heated to 130° C. to 170° C. for 4 hours. The crude reaction mixture was cooled, suspended in a minimal amount of MeOH: CH₂ Cl₂ (1:19), loaded directly onto a normal phase flash chromatography column, and the crude dye was eluted with an MeOH: CH₂ Cl₂ (1:19) mobile phase. When necessary, the dye was purified and separated into distinct isomers 35 and 36 by PTLC developed with MeOH: CH₂ Cl₂ (1:9). The isomerically pure dye, which migrated as a single spot on silica TLC eluting with 1:9 MeOH:CH₂ Cl₂, was identified by its UV/Visible absorption spectra and its long wavelength fluorescent excitation and emission spectra.

General Procedure B (FIG. 6). In the general procedure outlined in FIG. 6, a solid phthalic anhydride derivative 34 (100 mg) was placed in a round bottom flask capped with a rubber septa and purged with dry argon. Dry nitrobenzene (2 mL) was added and heated to dissolve the anhydride. The mixture was cooled to room temperature and 3 to 6 equivalents of anhydrous AlCl₃ was added with stirring to dissolve the solid. Subsequently, 1 equivalent of a 1-amino-3-methoxynapthalene intermediate 31 was added with stirring and the reaction was heated to 130° C. for 1 hour. The reaction was then cooled and suspended in EtOAc. The organic layer was washed with saturated NH₄ Cl and brine, dried over Na₂ SO₄, filtered, and the solvent was removed in vacuo. When necessary, the resulting ketone intermediate 37/38 was purified and separated into distinct isomers 37 and 38 using normal phase flash chromatography using (MeOH: CH₂ Cl₂, 1:19) as the mobile phase, or by recrystallization. The methoxy group of the isomerically pure intermediate 37 or 38 was removed according to the general boron tribromide deprotection procedure described in Example 1 to give amino-hydroxynapthalene ketone 39. The amino-hydroxynapthalene ketone 39 (100 mg) was then reacted at 130° C. with 1 equivalent of a 1-amino-3-napthalene intermediate 32 in dry 1,2-dichlorobenzene (2 mL) for 2 hours. The reaction was cooled, giving isomerically pure and asymmetrically substituted product 40 that was purified as in General Procedure A above.

Synthesis of Dibenzorhodamine Dye 41 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, and 1-diethylamino-3-hydroxynapthalene 4 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 42 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, and N-methyl-5-hydroxy-benzoquinoline 15 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 43 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, and 5-hydroxy-benzoquinoline 17 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 44 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, the N-methyl-2,2,4-trimethyl-5-hydroxy-benzoquinoline 22 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 45 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, and N-methyl-3,3-dimethyl-4-hydroxy-benzoindoline 27 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 46 (FIG. 7)

General procedure A was followed employing tetrafluorophthalic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 to C-17 are F, and N-ethyl-3,3-4-hydroxy-benzoindoline 29 as the aminohydroxy intermediate 31.

Synthesis of Dibenzorhodamine Dye 47 (FIG. 7)

General procedure A was followed employing dichlorotrimellitic anhydride as the phthalic anhydride derivative, i.e., compound 34 where the substituents at C-14 and C-17 are Cl and the substituent at C-15 is CO₂ H, and N-phenyl-3,3-dimethyl-4-hydroxy-benzoindoline 9 as the aminohydroxy intermediate 31.

Example 9 Spectral Properties of Selected Dibenzorhodamine Dye Compounds

The following table presents important spectral properties of several representative dibenzorhodamine dye compounds of the invention. All spectra were recorded at room temperature, in 1×TBE buffer and 8 M urea, for the free dye having absorption at the dye's λ_(max), abs. Dye concentration was approximately 10⁻⁶ M.

    ______________________________________                                                Absorption   Emission   Full Width at                                     Dye Maximum (nm) Maximum (nm) Half Max (nm)                                  ______________________________________                                         41     585          614        59                                                42 609 634 42                                                                  43 597 637 47                                                                  44 598 640 50                                                                  45 639 650 31                                                                  46 639 652 33                                                                  47 632 676 66                                                                ______________________________________                                    

Example 10 Synthesis of 3,3-dimethyl-hydroxy-benzoindoline 25 (FIGS. 8 and 9)

Compound 2 was converted to 1-amino-3-methoxynapthalene 18 using the palladium-catalyzed triflate/imine coupling and hydrolysis procedure of Buchwald (Buchwald, S. L. et al Tetrahedron Letters, 1997, 38/36, 6367-6370) as follows (FIG. 8).

The 3-methoxy-napthalene-1-triflate 2 (25 g) was mixed with 0.013 equivalents of tris(dibenzylideneacetone)-dipalladium (Pd₂ (dba)₃), 0.04 equivalents of racemic 2,2'-bis(diphenylphosphino)-1,1'-binapthyl (±BINAP), 1.3 equivalents of potassium carbonate, 1.3 equivalents of cesium carbonate, and 1.5 equivalents of benzophenone imine. Alternatively, potassium or sodium t-butoxide (2.6 equivalents) could be used as a substitute base for the reaction. The reaction mixture was suspended in 75 mL of dry toluene and 75 mL of dry tetrahydrofuran and stirred for 24 hours at 120° C. in an oil bath. A mixture of 75 mL of hexane/ethyl acetate (9:1) was added to the reaction mixture, and the mixture was eluted through silica gel with hexane/ethyl acetate (3:2). The elutant was collected and then concentrated under reduced pressure. To the concentrated oil, hexane/ethyl acetate (9:1) was added to crystallize out 1-benzophenone imino-3-methoxynapthalene 49 as yellow crystals (20.0 g, 72.6%/). The mother liquor was concentrated and hexane/ethyl acetate (9:1) was added to crystallize out a second crop of 49 as yellow crystals (3.0 g, 10.9%). (Total yield: 83.5%).

Compound 49 was hydrolyzed under acid conditions to give 18 as follows. Compound 49 (27 gm) was suspended in 150 mL of 1,4-dioxane and 100 mL of 5% sulfuric acid (H₂ SO₄). The reaction was then heated and stirred for 1 hour at 50° C. in an oil bath. The reaction mixture was cooled to room temperature and washed with 150 mL of hexane/ethyl acetate (3:2). The solution was then basified with ice cold aqueous NaOH to pH 10-11, and extracted three times with ethyl acetate. The combined organic extract was dried with sodium sulfate (Na₂ SO₄) and evaporated under reduced pressure to give 18 as pale brown oil which crystallized upon standing (13.9 g, 100%).

Compound 25, 3,3-dimethyl-hydroxy-benzoindoline, was synthesized from 18 according to the procedure described above in Example 6.

Example 11 Synthesis of N-Substituted Methoxybenzoindoline Intermediates 57-61 (FIG. 9)

Compound 25 was employed as a common intermediate to synthesize the N-substituted derivatives 57-61 by either alkylative substitution or palladium catalysed coupling to the secondary amine group (FIG. 9).

Synthesis of N-(6-hexanoic acid)-3,3-dimethyl-hydroxy-benzoindoline 57

Compound 25 (2.3 g) was alkylated by treating with 3 equivalents of commercially available methyl-6-iodohexanoic acid 52 and 3 equivalents of diisopropylethylamine. The mixture was suspended in 23 mL of dry toluene and heated at 130° C. in an oil bath with stirring for 18 hours. The solvent was evaporated under reduced pressure to give crude N-(6-hexanoic acid)-3,3-dimethyl-hydroxy-benzoindoline 57. Crude 57 was dissolved in dichloromethane and purified by normal phase flash chromatography eluting with hexane/ethyl acetate (99:1)(yield 2.55 g, 74%).

Synthesis of N-(biphenyl)-3,3-dimethyl-hydroxy-benzoindoline 58

Compound 25 (2.3 g) was N-arylated by palladium catalysed coupling according to the established procedure (Buchwald, et al J. Org., 1997, 62, 6066-6068) as follows: Compound 25 (2 g) was mixed with 1.4 equivalents of 4-bromo-biphenyl 7, sodium t-butoxide 1.3 equivalents), 0.013 equivalents of tris(dibenzylideneacetone)dipalladium Pd₂ (dba)₃), 0.04 equivalents of racemic 2,2'-bis(diphenylphosphino)-1,1'-binapthyl (±BINAP). The reaction mixture was suspended in 100 mL of dry toluene, stirred well, and heated at 130° C. in an oil bath overnight (16 hrs.). The reaction mixture was quenched with aqueous ammonium chloride (NH₄ Cl) and extracted (3×) with ethyl acetate. The organic extract was dried with anhydrous Na₂ SO₄. Hexane (equal volume) was added to the crude reaction mixture and it was eluted through silica-gel with hexane/ethyl acetate (1:1). The solvent was evaporated under reduced pressure and the residue was purified by normal phase flash chromatography eluting with hexane/ethyl acetate (98:2) to give N-(biphenyl)-3,3-dimethyl-hydroxy-benzoindoline 58 (yield 85%) as white powder.

Synthesis of N-(carboxybiphenyl)-3,3-dimethyl-hydroxy-benzoindoline 59

Compound 54 was synthesized from commercially available bromo-biphenyl-methyl ketone by a haloform reaction to give the bromo-biphenyl acid, followed by esterification employing established procedures. Compound 25 was N-arylated with 54 according to the established procedure (Buchwald, et al Tetrahedron Letters, 1997, 38/36, 6359-6362) as follows: Compound 25 (0.4 g) was mixed with 1.4 equivalents of compound 54, 0.013 equivalents of tris(dibenzylideneacetone)dipalladium (Pd₂ (dba)₃), 0.04 equivalents of racemic 2,2'-bis(diphenylphosphino)-1,1'-binapthyl (±BINAP), and 3 equivalents of cesium carbonate. The reaction mixture was suspended in 100 mL of dry toluene and 100 mL of dry tetrahydrofuran, then heated at 130° C. in an oil bath and stirred for 18 hours. The reaction was cooled and hexane (30 mL) was added to the crude mixture. The crude product was eluted through silica-gel with hexane/ethyl acetate (3:2). The solvent was removed under reduced pressure and the N-(carboxybiphenyl)-3,3-dimethyl-hydroxy-benzoindoline 59 was purified by normal phase phase flash chromatography eluting with hexane/ethyl acetate: (95:5) (bright yellow solid yield 0.25 g, 32%).

Synthesis of N-phenyl-3,3-dimethyl-hydroxy-benzoindoline 60

Compound 25 was N-arylated with iodobenzene or bromobenzene as described above for synthesis of compound 58 from compound 25. Pure N-phenyl-3,3-dimethyl-hydroxy-benzoindoline 8 was isolated after normal phase flash chromatography employing hexane/ethyl acetate: (98:2).

Synthesis of N-carboxyphenyl-3,3dimethyl-hydroxy-benzoindoline 61

Compound 25 was N-arylated with methyl iodobenzoate or methyl bromobenzoate as described above for synthesis of compound 59. Pure N-carboxyphenyl-3,3-dimethyl-hydroxy-benzoindoline 61 was isolated after normal phase flash chromatography employing hexane/ethyl acetate: (95:5).

Example 12 Synthesis of Dibenzorhodamine Dyes 67, 72, 76 and 81 (FIGS. 10-13) Synthesis of Joda 4-Dye 67 (FIG. 10)

Hydroxyindoline 62 was obtained by demethylation of compound 58 using aluminium chloride (AlCl₃) according to the following procedure: Compound 58 (2 g), and aluminium chloride (6 g) were thoroughly mixed under a strong stream of argon and the reaction mixture purged for 10 minutes with argon. The solid mixture was heated under Argon in an oil bath from 90° C. to 120° C. over 20 min. The reaction mixture was cooled and the solids suspended in dichloromethane and transferred into a solution of ice and dilute H₂ SO₄. The aqueous layer was extracted five times, the combined organic extract was washed with saturated sodium chloride, and dried over sodium sulfate. After filtration, the solvent was evaporated under reduced pressure and pure 62 (0.13 g) was isolated after normal phase flash chromatography eluting with dichloromethane/methanol (99:1). Hydroxyindoline 63 was generated from compound 59 employing the same procedure as that for conversion of compound 58 to compound 62.

Next, one equivalent of a 1:1 complex of N-methylformanilide and phosphorous oxychloride in dry dichloromethane was added to one equivalent of 62 in a small pear flask (100 mg in a 5 ml flask). The reaction mixture was heated at 80° C. in an oil bath under a stream of Argon until the dichloromethane was evaporated leaving a dark red oil. Nitrobenzene (300 ul) was added followed by addition of 2 equivalents of POCl₃. To the above solution was added one equivalent of 63 suspended in nitrobenzene (500 ul). The reaction mixture was heated from 80° C. to 155° C. over 25 min. and then kept at 155° C. for 15 minutes. The reaction was cooled and transferred with dichloromethane to 5% HCl. The aqueous layer was saturated with brine and extracted 3× with dichloromethane. The combined organic extracts were separated and evaporated under reduced pressure to give the crude dye derivative 64. Crude 64 was suspended in acetic acid (3 ml) and 5% HCl (3 ml) and heated at 60° C. for 1 hour. The reaction mixture was then poured into a solution of ice, saturated aqueous sodium chloride, and extracted 3 times with dichloromethane. After evaporation of the combined organic layers, the pure mono-carboxylated asymmetric dye derivative 65 was then purified from the other two symmetric dye products, the bis-biphenyl and bis-carboxybiphenyl dyes, by normal phase flash chromatography eluting with dichloromethane/methanol (9:1).

Finally, the purified dye derivative 65 was sulfonated to give Joda-4 dye 67 as follows. Dye derivative 65 (30 mg) and 3 equivalents of anhydrous sodium sulfate were suspended in dry dichloromethane (50 mL) at 0° C. under Argon. To the above solution, 5 equivalents of chlorosulfonic acid (ClSO₃ H) were added and the reaction mixture was stirred at room temperature for 18 hours. The reaction mixture was quenched with saturated aqueous sodium chloride/5% HCl and the aqueous layer extracted 3 times with dichloromethane. The organic extract was evaporated under reduced pressure to give crude Joda-4 dye 66. Crude dye 66 was suspended in a solution of dioxane and 5% HCl (2:1) and stirred at room temperature for 20 hours. The solution was then concentrated under reduced pressure, suspended in saturated aqueous sodium chloride and extracted 3 times with dichloromethane. The solvent was evaporated to give crude Joda 4 dye 67. Pure Joda 4 dye 67 was isolated by normal phase preparative thin layer chromatography (PTLC) developed with methanol/dichloromethane (1:4) or flash chromatography eluting with methanol/dichloromethane (1:9).

Synthesis of Joda-3 Dye 72 (FIG. 11)

Compound 61 was demethylated to give compound 68, and compound 8 was demethylated to give compound 9, both employing the aluminum chloride deprotection procedure described above for conversion of compound 58 to compound 62. Compound 68 was reacted with the methyl formanilide/POCl₃ complex, and subsequently with compound 9 to generate dye derivative 70 as described for the synthesis of dye derivative 64 from compound 62 and 63. Crude dye derivative 70 was hydrolysed by acid to give dye derivative 71 according to the procedure for generation of dye derivative 65 from 64 above. The pure asymmetric dye derivative 71 was purified by PTLC from the two symmetric bis-phenyl and bis-carboxyphenyl dye products. The purified dye 71 was then sulfonated and hydrolysed to give crude Joda-3 dye 72 as described above for generation of Joda-4 dye 67 from dye derivative 65. Pure Joda-3 dye 72 was isolated by normal phase preparative thin layer chromatography (PTLC) developed with methanol/dichloromethane (1:4) or flash chromatography eluting with methanol/dichloromethane (1:9).

Synthesis of Joda-2 Dye 76 (FIG. 12)

Compound 57 was demethylated to give compound 73 by boron tribromide deprotection, and compound 8 was demethylated to give 9 employing the aluminum chloride deprotection procedure described above for conversion of compound 58 to compound 62. Compound 57 reacted with the methyl formanilide/POCl₃ complex under the standard conditions, and subsequently with compound 9 under the standard conditions to generate dye derivative 74 as described above in Example 7. Crude dye derivative 74 was hydrolysed by standard acid hydrolysis to give dye derivative 75. The pure asymmetric dye derivative 75 was purified by PTLC from the two symmetric bisphenyl and bis-hexanoic dye products. The purified dye 75 was then sulfonated by the standard procedure described for formation of 67 from 65 to give crude Joda-3 dye 76. Pure Joda-2 dye 76 was isolated by normal phase preparative thin layer chromatography (PTLC) developed with methanol/dichloromethane (1:4) or flash chromatography eluting with methanol/dichloromethane (1:9).

Synthesis of Joda-1 Dye 81. (FIG. 13)

Compound 57 (0.313 g) was saponified by treatment with 7 equivalents of 1M KOH in methanol at room temperature over 3 hours. The solution was concentrated to dryness and the oil extracted well with ethyl acetate and 5% hydrochloric acid solution. The organic layer was dried with sodium sulfate and concentrated to a colorless oil. Pure 77 was isolated by normal phase chromatography eluting with 5% methanol/dichloromethane/0.1% acetic acid (yield 0.243 g; 84%).

Next, compound 77 (0.360 gm) was dissolved in dry dichloromethane (2 ml) and a solution of dichloromethylmethyl ether (2.6 equivalents) and tin tetrachloride (4 equivalents). The solution was refluxed for 1.5 hrs. The mixture was extracted with ethyl acetate and 3M hydrochloric acid solution. The organic layer was washed with water and brine, dried over anhydrous Na₂ SO₄, concentrated to an oil, and used without purification. There was an approximately equimolar mixture of compound 77 and 78 at this point, based on thin layer chromatography. This oil was dissolved in dry dichloromethane (8 ml), and cooled to -78° C. Demethylation of the mixture was carried out by established boron tribromide procedures to yield a mixture of Compounds 79 and 80. The resultant crude oil was dissolved in dry dichloromethane (5 ml) and phosphorus oxychloride (2 equivalents) was added; nitrobenzene (5 ml) was then added. The mixture was heated from 80 to 150° C. over 45 minutes and promptly removed from heat. The workup and isolation was performed as in Example 12 for the synthesis of compound 67 to yield crude Joda 1 dye 81. Pure dye 81 was isolated by PTLC as described in Example 12 for the synthesis of compound 67, yielding 32 mg.

Example 13 Synthesis of Dye Carboxy N-Hydroxysuccinimide Derivatives of Compounds 67, 72, 76, and 81 and Coupling the Derivatives to Nucleotides and Polynucleotides (FIGS. 14 and 15)

The N-hydroxysuccinimide (NHS) derivatization of the carboxylic acid dyes 67, 72, 76, and 81 was accomplished by one of two methods. For synthesis of the Joda 4 dye NHS 82, Joda 3 dye NHS 83, and Joda 2 dye NHS 84 the preferred method (Method A) employed O-(N-succinimidyl)-N,N,N',N'-tetramethyluronium tetrafluoroborate reagent, while for Joda 1 dye 85 the preferred method Method B) employed dicyclohexylcarbodiimide (DCC) and N-hydroxysuccinimide.

Method A: The dye was suspended in dry DMF (5 mg dye: 300 ul DMF) with 6 equivalents of diisopropyl-ethyl amine. To the dye solution was added 15 equivalents of O-(N-succinimidyl)-N,N,N',N'-tetramethyluronium tetrafluoroborate and the reaction was stirred for 15 minutes at room temperature. The reaction was transferred with dichloromethane into 5% HCl (20 ml). The aqueous layer was made salty by addition of saturated NaCl and extracted 3 times with dichloromethane. The combined organic layers were concentrated to dryness and the crude dye-NHS purified by normal phase flash chromatography eluting with MeOH/CH₂ Cl₂ (1:9).

Method B: The dye and 20 equivalents of N-hydroxysuccinimide were suspended in dry dichloromethane (5 mg: 500 ul CH₂ Cl₂). Mine equivalents of dicyclohexylcarbodiimide were added and the reaction was stirred for 1 hour at room temperature. The reaction was quenched and the pure dye-NHS isolated as for Method A.

Attachment of the NHS derivatives to nucleotides and polynucleotides was performed as follows. Amino group substituted oligomer or terminator was suspended in formamide (5×10⁻⁴ M) and 15 equivalents of diisopropylethylamine were added. An excess (5-10 equivalents) of dye-NHS suspended in DMSO (5 mg/60 ul) were added with stirring at room temperature. The reaction was stirred at room temperature for 4 hours. To the reaction mixture was added 3 M NaOAc to give 0.5 M NaOAc. Four times the reaction volume of EtOH were added and the mixture was cooled. The precipitated dye labeled oliomer was isolated by centrifugation and purified by reverse phase HPLC eluting with 30% AcCN/0.1×TEAA buffer.

All publications, patents, and patent applications referred to herein are hereby incorporated by reference to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference.

Although only a few embodiments have been described in detail above, those having ordinary skill in the chemical arts will clearly understand that many modifications are possible in these embodiments without departing from the teachings thereof. All such modifications are intended to be encompassed within the scope of the following claims. 

We claim:
 1. A dibenzorhodamine compound having the structure ##STR25## including nitrogen- and aryl-substituted forms thereof, and with the proviso that C-7 is bonded to hydrogen.
 2. The compound of claim 1 comprising a first bridging group which when taken together with the C-12-bonded nitrogen and the C-12 and C-13 carbons forms a first ring structure having from 4 to 7 members; and/ora second bridging group which when taken together with the C-2-bonded-nitrogen and the C-1 and C-2 carbons forms a second ring structure having from 4 to 7 members.
 3. The compound of claim 2 wherein one or both of the first and second ring structures has five members.
 4. The compound of claim 3 wherein the five membered ring structure includes one gem disubstituted carbon.
 5. The compound of claim 1 comprising one or more nitrogen substituents selected from the group consisting of lower alkyl, lower alkene, lower alkyne, phenyl, benzyl, aryl, heterocycle, polycyclic aromatic, water-solubilizing group, and linking group, including substituted forms thereof.
 6. The compound of claim 5 wherein the linking group is isothiocyanate, sulfonyl chloride, 4,6-dichlorotriazinyl, succinimidyl ester, activated ester, pentafluorophenyl ester, maleimide, haloacetyl, iodoacetamide, and N-hydroxysuccinimidyl ester.
 7. The compound of claim 5 wherein the water-solubilizing group is carboxylate, sulfonate, sulfate, phosphonate, phosphate, quaternary amine, sulfate, polyhydroxyl, and water-soluble polymer.
 8. The compound of claim 4 wherein the gem substituents are lower alkyl.
 9. The compound of claim 8 wherein the gem substituents are methyl.
 10. The compound of claim 3 wherein the five membered ring is not aromatic.
 11. The compound of claim 3 wherein the five membered ring is substituted with linking group or water-solubilizing group.
 12. The compound of claim 2 wherein the first and second ring structures are the same.
 13. The compound of claim 2 wherein the first and second ring structures are different.
 14. The compound of claim 1 comprising one or more nitrogen substituted forms --L--R, wherein:L is selected from the group consisting of lower alkyl, lower alkene, lower alkyne, phenyl, benzyl, aryl, heterocycle, and polycyclic aromatic; and R is H, water-solubilizing group, and linking group.
 15. The compound of claim 9 wherein the water-solubilizing group is carboxylate, sulfonate, sulfate, phosphonate, phosphate, quaternary amine, sulfate, polyhydroxyl, and water-soluble polymer.
 16. The compound of claim 10 wherein the linking group is isothiocyanate, sulfonyl chloride, 4,6-dichlorotriazinyl, succinimidyl ester, activated ester, pentafluorophenyl ester, maleimide, haloacetyl, iodoacetamide, and N-hydroxysuccinimidyl ester.
 17. The compound of claim 1 comprising a third bridging group which when taken together with the C-12-bonded nitrogen and the C-11 and C-12 carbons forms a third ring structure having from 5 to 7 members; and/ora fourth bridging group which when taken together with the C-2-bonded nitrogen and the C-2 and C-3 carbons forms a fourth ring structure having from 5 to 7 members.
 18. The compound of claim 17 wherein one or both of the third and fourth ring structures has six members.
 19. The compound of claim 18 wherein the six membered ring structure includes one gem disubstituted carbon.
 20. The compound of claim 19 wherein the gem substituents are lower alkyl.
 21. The compound of claim 19 wherein the gem substituents are methyl.
 22. The compound of claim 18 wherein the six membered ring is not aromatic.
 23. The compound of claim 17 wherein one or both of the third and fourth ring structures has five members.
 24. The compound of claim 23 wherein the five membered ring structure includes one gem disubstituted carbon.
 25. The compound of claim 24 wherein the gem substituents are lower alkyl.
 26. The compound of claim 24 wherein the gem substituents are methyl.
 27. The compound of claim 1 comprising one or more substituents at one or more of positions C-1, C-3 to C-6, C-8 to C-11, and C-13, selected from the group consisting of fluorine, chlorine, lower alkyl, lower alkene, lower alkyne, sulfate, sulfonate, sulfone, sulfonamide, sulfoxide, amino, ammonium, amido, nitrile, lower alkoxy, phenoxy, phenyl, aryl, polycyclic aromatic, heterocycle, water-solubilizing group, and linking group, including substituted forms thereof.
 28. The compound of claim 27 comprising a fused aromatic ring bonded across the C-3 and C-4 carbons, the C-4 and C5 carbons, the C-9 and C-10 carbons, and/or the C-10 and C-11 carbons, including substituted forms thereof.
 29. The compound of claim 28 comprising a fused aromatic ring bonded across the C-3 and C-4 carbons and the C-10 and C11 carbons, including substituted forms thereof.
 30. The compound of claim 28 comprising a fused aromatic ring bonded across the C-9 and C-10 carbons and the C-4 and C-5 carbons, including substituted forms thereof.
 31. The compound of claim 27 wherein the one or more substituents are sulfonate.
 32. The compound of claim 1 having the structure ##STR26## wherein L₁ and L₂ are selected from the group consisting of ##STR27## disubstituted phenyl, disubstituted biphenyl, disubstituted napthyl, and --(CH₂)_(n) -- where n ranges from 1 to 8; andR₁ and R₂ are selected from the group consisting of linking group and water-solubilizing group.
 33. The compound of claim 32 wherein the water solubilizing group is selected from the group consisting of carboxylate, sulfonate, sulfate, phosphonate, phosphate, quaternary amine, polyhydroxyl, and water-soluble polymer.
 34. The compound of claim 32 wherein the linking group is isothiocyanate, sulfonyl chloride, 4,6-dichlorotriazinyl, succinimidyl ester, activated ester, pentafluorophenyl ester, maleimide, haloacetyl, iodoacetamide, and N-hydroxysuccinimidyl ester.
 35. The compound of claim 32 comprising a fused aromatic ring bonded across the C-3 and C-4 carbons, the C-4 and C-5 carbons, the C-9 and C-10 carbons, or the C-10 and C-11 carbons, including substituted forms thereof.
 36. The compound of claim 5 comprising a fused aromatic ring bonded across the C-3 and C-4 carbons and the C-10 and C-11 carbons, including substituted forms thereof.
 37. The compound of claim 35 comprising a fused aromatic ring bonded across the C-9 and C-10 carbons and the C-4 and C-5 carbons, including substituted forms thereof.
 38. The compound of claim 1 having the structure ##STR28##
 39. The compound of claim 1 having the structure
 40. The compound of claim 1 having the structure
 41. The compound of claim 1 having the structure
 42. The compound of claim 1 having the structure
 43. The compound of claim 1 having the structure
 44. The compound of claim 1 having the structure
 45. The compound of claim 1 having the structure
 46. The compound of claim 1 having the structure wherein:L₁ and L₂ are selected from the group consisting of ##STR29## disubstituted phenyl, disubstituted biphenyl, disubstituted napthyl, and --(CH₂)_(n) -- where n ranges from 1 to 8; and R₁ and R₂ are selected from the group consisting of H, linking group and water-solubilizing group.
 47. The compound of claim 46 wherein the water solubilizing group is selected from the group consisting of carboxylate, sulfonate, sulfate, phosphonate, phosphate, quaternary amine, polyhydroxyl, and water-soluble polymer.
 48. The compound of claim 46 wherein the linking group is isothiocyanate, sulfonyl chloride, 4,6-dichlorotriazinyl, succinimidyl ester, activated ester, pentafluorophenyl ester, maleimide, haloacetyl, iodoacetamide, and N-hydroxysuccinimidyl ester.
 49. The compound of claim 1 having the structure ##STR30##50.
 50. The compound of claim 1 having the structure
 51. The compound of claim 1 having the structure 